0001558370-21-001828 | 10-K | XBRL Viewer

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2020	Feb. 19, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Document Transition Report	false
Entity File Number	1-13011
Entity Registrant Name	Comfort Systems USA, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	76-0526487
Entity Address, Address Line One	675 Bering Drive
Entity Address, Address Line Two	Suite 400
Entity Address, City or Town	Houston
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77057
City Area Code	713
Local Phone Number	830-9600
Title of 12(b) Security	Common Stock, $.01 par value
Trading Symbol	FIX
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 1,450
Entity Common Stock, Shares Outstanding		36,185,179
Entity Central Index Key	0001035983
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--12-31
Amendment Flag	false
ICFR Auditor Attestation Flag	true

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
CURRENT ASSETS:
Cash and cash equivalents	$ 54,896	$ 50,788
Billed accounts receivable, less allowance for credit losses of $9,087 and $6,907, respectively	619,544	619,037
Unbilled accounts receivable, less allowance for credit losses of $784 and $0, respectively	45,596	55,542
Other receivables, less allowance for credit losses of $759 and $0, respectively	44,212	37,632
Inventories	13,472	10,053
Prepaid expenses and other	15,510	14,396
Costs and estimated earnings in excess of billings, less allowance for credit losses of $79 and $0, respectively	18,622	2,736
Total current assets	811,852	790,184
PROPERTY AND EQUIPMENT, NET	117,206	109,796
LEASE RIGHT-OF-USE ASSET	94,727	84,073
GOODWILL	464,392	332,447
IDENTIFIABLE INTANGIBLE ASSETS, NET	231,807	159,974
DEFERRED TAX ASSETS	29,401	21,923
OTHER NONCURRENT ASSETS	7,970	6,615
Total assets	1,757,355	1,505,012
CURRENT LIABILITIES:
Current maturities of long-term debt		20,817
Accounts payable	204,145	196,195
Accrued compensation and benefits	121,864	102,891
Billings in excess of costs and estimated earnings	226,237	166,918
Accrued self-insurance	49,166	39,546
Other current liabilities	91,492	81,630
Total current liabilities	692,904	607,997
LONG-TERM DEBT, NET	235,733	205,318
LEASE LIABILITIES	80,576	72,697
DEFERRED TAX LIABILITIES	1,339	1,425
OTHER LONG-TERM LIABILITIES	50,374	32,271
Total liabilities	1,060,926	919,708
COMMITMENTS AND CONTINGENCIES
STOCKHOLDERS' EQUITY:
Preferred stock, $.01 par, 5,000,000 shares authorized, none issued and outstanding
Common stock, $.01 par, 102,969,912 shares authorized, 41,123,365 and 41,123,365 shares issued, respectively	411	411
Treasury stock, at cost, 4,935,186 and 4,465,448 shares, respectively	(129,243)	(103,960)
Additional paid-in capital	322,451	320,168
Retained earnings	502,810	368,685
Total stockholders' equity	696,429	585,304
Total liabilities and stockholders' equity	$ 1,757,355	$ 1,505,012

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
CONSOLIDATED BALANCE SHEETS
Billed accounts receivable, allowance for credit losses (in dollars)	$ 9,087	$ 6,907
Unbilled accounts receivable, allowance for credit losses (in dollars)	784	0
Other receivables, allowance for credit losses (In dollars)	759	0
Costs and estimated earnings in excess of billings, allowance for credit losses	$ 79	$ 0
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	102,969,912	102,969,912
Common stock, shares issued	41,123,365	41,123,365
Treasury stock, shares	4,935,186	4,465,448

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
CONSOLIDATED STATEMENTS OF OPERATIONS
REVENUE	$ 2,856,659	$ 2,615,277	$ 2,182,879
COST OF SERVICES	2,309,676	2,113,334	1,736,600
Gross profit	546,983	501,943	446,279
SELLING, GENERAL AND ADMINISTRATIVE EXPENSES	357,777	340,005	296,986
GAIN ON SALE OF ASSETS	(1,445)	(1,701)	(945)
Operating income	190,651	163,639	150,238
OTHER INCOME (EXPENSE):
Interest income	103	224	73
Interest expense	(8,385)	(9,317)	(3,710)
Changes in the fair value of contingent earn-out obligations	9,119	(2,991)	(2,066)
Other	52	187	4,141
Other income (expense)	889	(11,897)	(1,562)
INCOME BEFORE INCOME TAXES	191,540	151,742	148,676
PROVISION FOR INCOME TAXES	41,401	37,418	35,773
NET INCOME	$ 150,139	$ 114,324	$ 112,903
INCOME PER SHARE:
Basic (in shares)	$ 4.11	$ 3.10	$ 3.03
Diluted (in shares)	$ 4.09	$ 3.08	$ 3.00
SHARES USED IN COMPUTING INCOME PER SHARE:
Basic (in shares)	36,542	36,854	37,202
Diluted (in shares)	36,738	37,131	37,592
DIVIDENDS PER SHARE (in dollars per share)	$ 0.425	$ 0.395	$ 0.330

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Cumulative Effect, Period of Adoption, Adjustment [Member] Retained Earnings	Cumulative Effect, Period of Adoption, Adjustment [Member]	Common Stock	Treasury Stock	Additional Paid-In Capital	Retained Earnings	Total
BALANCE at Dec. 31, 2017			$ 411	$ (63,519)	$ 312,784	$ 168,269	$ 417,945
BALANCE (in shares) at Dec. 31, 2017			41,123,365
BALANCE (in shares) at Dec. 31, 2017				(3,936,291)
Increase (Decrease) in Stockholders' Equity
Net income						112,903	112,903
Issuance of Stock:
Issuance of shares for options exercised				$ 3,618	(513)		3,105
Issuance of shares for options exercised (in shares)				206,875
Issuance of restricted stock & performance stock				$ 2,227	(4)		2,223
Issuance of restricted stock & performance stock (in shares)				129,569
Shares received in lieu of tax withholding payment on vested restricted stock				$ (1,540)			(1,540)
Shares received in lieu of tax withholding payment on vested restricted stock (in shares)				(36,967)
Stock-based compensation					4,212		4,212
Dividends						(12,268)	(12,268)
Share repurchase				$ (28,533)			(28,533)
Share repurchase (in shares)				(592,839)
BALANCE at Dec. 31, 2018			$ 411	$ (87,747)	316,479	268,904	498,047
BALANCE (in shares) at Dec. 31, 2018			41,123,365
BALANCE (in shares) at Dec. 31, 2018				(4,229,653)
Increase (Decrease) in Stockholders' Equity
Net income						114,324	114,324
Issuance of Stock:
Issuance of shares for options exercised				$ 2,532	(182)		2,350
Issuance of shares for options exercised (in shares)				114,125
Issuance of restricted stock & performance stock				$ 2,303	(297)		2,006
Issuance of restricted stock & performance stock (in shares)				107,606
Shares received in lieu of tax withholding payment on vested restricted stock				$ (1,498)			(1,498)
Shares received in lieu of tax withholding payment on vested restricted stock (in shares)				(28,586)
Stock-based compensation					4,168		4,168
Dividends						(14,543)	(14,543)
Share repurchase				$ (19,550)			(19,550)
Share repurchase (in shares)				(428,940)
BALANCE at Dec. 31, 2019			$ 411	$ (103,960)	320,168	368,685	$ 585,304
BALANCE (in shares) at Dec. 31, 2019			41,123,365				41,123,365
BALANCE (in shares) at Dec. 31, 2019				(4,465,448)			4,465,448
Increase (Decrease) in Stockholders' Equity
Net income						150,139	$ 150,139
Issuance of Stock:
Issuance of shares for options exercised				$ 2,811	(667)		2,144
Issuance of shares for options exercised (in shares)				113,731
Issuance of restricted stock & performance stock				$ 3,102	(1,247)		1,855
Issuance of restricted stock & performance stock (in shares)				128,889
Shares received in lieu of tax withholding payment on vested restricted stock				$ (1,076)			(1,076)
Shares received in lieu of tax withholding payment on vested restricted stock (in shares)				(27,724)
Stock-based compensation					4,197		4,197
Dividends						(15,499)	(15,499)
Share repurchase				$ (30,120)			(30,120)
Share repurchase (in shares)				(684,634)
BALANCE at Dec. 31, 2020	$ (515)	$ (515)	$ 411	$ (129,243)	$ 322,451	$ 502,810	$ 696,429
BALANCE (in shares) at Dec. 31, 2020			41,123,365				41,123,365
BALANCE (in shares) at Dec. 31, 2020				(4,935,186)			4,935,186

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 150,139	$ 114,324	$ 112,903
Adjustments to reconcile net income to net cash provided by operating activities-
Amortization of identifiable intangible assets	32,698	27,082	20,089
Depreciation expense	27,931	24,490	22,600
Change in right-of-use assets	16,692	16,887
Bad debt expense	5,253	2,978	3,562
Deferred tax provision (benefit)	(7,953)	(4,251)	4,456
Amortization of debt financing costs	544	387	383
Gain on sale of assets	(1,445)	(1,701)	(945)
Changes in the fair value of contingent earn-out obligations	(9,119)	2,991	2,066
Stock-based compensation	6,934	5,878	7,161
(Increase) decrease in-
Receivables, net	38,486	(49,508)	(68,621)
Inventories	(1,457)	2,366	(1,538)
Prepaid expenses and other current assets	(4,855)	(15,519)	519
Costs and estimated earnings in excess of billings and unbilled accounts receivable	2,706	(4,312)	(14,444)
Other noncurrent assets	(1,373)	(735)	(114)
Increase (decrease) in-
Accounts payable and accrued liabilities	11,087	31,046	47,871
Billings in excess of costs and estimated earnings	19,434	4,376	16,786
Other long-term liabilities	808	(14,751)	(5,544)
Net cash provided by operating activities	286,510	142,028	147,190
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(24,131)	(31,750)	(27,268)
Proceeds from sales of property and equipment	2,270	2,159	1,698
Proceeds from sale of business		1,611
Cash paid for acquisitions, net of cash acquired	(185,941)	(196,470)	(70,140)
Net cash used in investing activities	(207,802)	(224,450)	(95,710)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from revolving credit facility	268,000	356,000	124,000
Payments on revolving credit facility	(226,000)	(228,000)	(119,000)
Payments on term loan	(15,000)
Payments on other debt	(46,534)	(3,784)	(1,127)
Debt financing costs		(1,405)	(844)
Payments of dividends to stockholders	(15,499)	(14,543)	(12,268)
Share repurchase	(30,120)	(19,550)	(28,533)
Shares received in lieu of tax withholding	(1,076)	(1,498)	(1,540)
Proceeds from exercise of options	2,144	2,350	3,105
Deferred acquisition payments	(650)	(637)	(750)
Payments for contingent consideration arrangements	(9,865)	(1,343)	(5,445)
Net cash provided by (used in) financing activities	(74,600)	87,590	(42,402)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	4,108	5,168	9,078
CASH AND CASH EQUIVALENTS, beginning of period	50,788	45,620	36,542
CASH AND CASH EQUIVALENTS, end of period	$ 54,896	$ 50,788	$ 45,620

Business and Organization

12 Months Ended

Dec. 31, 2020

Business and Organization

Business and Organization

1. Business and Organization

Comfort Systems USA, Inc., a Delaware corporation, provides comprehensive mechanical and electrical contracting services, which principally includes heating, ventilation and air conditioning (“HVAC”), plumbing, electrical, piping and controls, as well as off-site construction, monitoring and fire protection. We install, maintain, repair and replace products and systems throughout the United States. Approximately 46.7% of our consolidated 2020 revenue is attributable to installation of systems in newly constructed facilities, with the remaining 53.3% attributable to maintenance, repair and replacement services. The terms “Comfort Systems,” “we,” “us,” or the “Company,” refer to Comfort Systems USA, Inc. or Comfort Systems USA, Inc. and its consolidated subsidiaries, as appropriate in the context.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2020

Summary of Significant Accounting Policies

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Principles of Consolidation

These financial statements are prepared in accordance with accounting principles generally accepted in the United States of America. The accompanying consolidated financial statements include our accounts and those of our subsidiaries in which we have a controlling interest. All significant intercompany accounts and transactions have been eliminated. Certain amounts in prior periods may have been reclassified to conform to the current period presentation. The effects of the reclassifications were not material to the consolidated financial statements.

Use of Estimates

The preparation of financial statements in conformity with generally accepted accounting principles requires the use of estimates and assumptions by management in determining the reported amounts of assets and liabilities, revenue and expenses and disclosures regarding contingent assets and liabilities. Actual results could differ from those estimates. The most significant estimates used in our financial statements affect revenue and cost recognition for construction contracts, self-insurance accruals, deferred tax assets, fair value accounting for acquisitions and the quantification of fair value for reporting units in connection with our goodwill impairment testing.

Cash Flow Information

We consider all highly liquid investments purchased with an original maturity of three months or less to be cash equivalents.

Cash paid (in thousands) for:


	Year Ended December 31,
	2020		2019		2018
Interest	$	7,684	$	8,817	$	3,743
Income taxes, net of refunds	$	51,286	$	45,288	$	33,401

Recent Accounting Pronouncements

In June 2016, the FASB issued ASU No. 2016-13, “Financial Instruments – Credit Losses (Topic 326).” The standard requires companies to consider historical experiences, current market conditions and reasonable and supportable forecasts in the measurement of expected credit losses. The standard requires us to accrue higher credit losses on financial assets compared to the legacy guidance on various items, such as contract assets and current receivables. ASU No. 2016-13 is effective for fiscal years beginning after December 15, 2019 and interim periods within those years. We adopted ASU No. 2016-13, “Financial Instruments – Credit Losses (Topic 326),” on January 1, 2020,

and the impact was not material to our overall financial statements. The adoption of ASU No. 2016-13 resulted in an increase in Allowance for Credit Losses of $0.7 million, an increase to Deferred Tax Assets of $0.2 million and an impact of $0.5 million to Retained Earnings.

In August 2018, the FASB issued ASU No. 2018-13, “Fair Value Measurement (Topic 820): Disclosure Framework — Changes to the Disclosure Requirements for Fair Value Measurement.” This standard removes certain disclosure requirements including the valuation processes for Level 3 fair value measurements, the policy for timing of transfers between levels and the amount of and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy. The standard requires certain additional disclosures for public entities, including disclosure of the changes in unrealized gains and losses included in Other Comprehensive Income for Level 3 fair value measurements and the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements. ASU No. 2018-13 is effective for fiscal years beginning after December 15, 2019 and interim periods within those years. Certain amendments, including the amendment on changes in unrealized gains and losses and the range and weighted average of significant unobservable inputs, should be applied prospectively while other amendments should be applied retrospectively to all periods presented upon their effective date. We have modified our fair value disclosures to conform with the requirements of ASU No. 2018-13, “Fair Value Measurement (Topic 820): Disclosure Framework — Changes to the Disclosure Requirements for Fair Value Measurement,” which we adopted on January 1, 2020.

In December 2019, the FASB issued ASU No. 2019-12, “Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes.” This standard simplifies the accounting for income taxes by eliminating certain exceptions to the guidance in Topic 740 related to the approach for intraperiod tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities for outside basis differences. The standard also simplifies aspects of the accounting for franchise taxes and enacted changes in tax laws or rates and clarifies the accounting for transactions that result in a step-up in the tax basis of goodwill. ASU No. 2019-12 is effective for fiscal years beginning after December 15, 2020 and interim periods within that year. Early adoption is permitted. We do not expect our adoption of this standard on January 1, 2021 to have a material impact on our consolidated financial statements.

Revenue Recognition

We recognize revenue over time for all of our services as we perform them because (i) control continuously transfers to that customer as work progresses, and (ii) we have the right to bill the customer as costs are incurred. The customer typically controls the work in process as evidenced either by contractual termination clauses or by our rights to payment for work performed to date plus a reasonable profit to deliver products or services that do not have an alternative use to the Company.

For the reasons listed above, revenue is recognized based on the extent of progress towards completion of the performance obligation. The selection of the method to measure progress towards completion requires judgment and is based on the nature of the products or services to be provided. We generally use the cost to cost measure of progress for our contracts, as it best depicts the transfer of assets to the customer that occurs as we incur costs on our contracts. Under the cost to cost measure of progress, the extent of progress towards completion is measured based on the ratio of costs incurred to date to the total estimated costs at completion of the performance obligation. Revenue, including estimated fees or profits, is recorded proportionally as costs are incurred. Costs to fulfill include labor, materials and subcontractors’ costs, other direct costs and an allocation of indirect costs.

For a small portion of our business in which our services are delivered in the form of service maintenance agreements for existing systems to be repaired and maintained, as opposed to constructed, our performance obligation is to maintain the customer’s mechanical system for a specific period of time. Similar to jobs, we recognize revenue over time; however, for service maintenance agreements in which the full cost to provide services may not be known, we generally use an input method to recognize revenue, which is based on the amount of time we have provided our services out of the total time we have been contracted to perform those services. Our revenue recognition policy is further discussed in Note 3 “Revenue from Contracts with Customers.”

Accounts Receivable and Allowance for Credit Losses

We are required to estimate and record the expected credit losses over the contractual life of our financial assets measured at amortized cost, including billed and unbilled accounts receivable, other receivables and costs and estimated

earnings in excess of billings. Accounts receivable include amounts from work completed in which we have billed or have an unconditional right to bill our customers. Our trade receivables are contractually due in less than a year.

We estimate our credit losses using a loss-rate method for each of our identified portfolio segments. Our portfolio segments are construction, service and other. While our construction and service financial assets are often with the same subset of customers and industries, our construction financial assets will generally have a lower loss-rate than service financial assets due to lien rights, which we are more likely to have on construction jobs. These lien rights result in lower credit loss expenses on average compared to receivables that do not have lien rights. Financial assets classified as “other” include receivables that are not related to our core revenue producing activities, such as receivables related to our acquisition activity from former owners, our vendor rebate program or receivables for estimated losses in excess of our insurance deductible, which are accrued with a corresponding accrued insurance liability.

Loss rates for our portfolios are based on numerous factors, including our history of credit loss expense by portfolio, the financial strength of our customers and counterparties in each portfolio, the aging of our receivables, our expectation of likelihood of payment, macroeconomic trends in the U.S. and the current and forecasted non-residential construction market trends in the U.S.

In addition to the loss-rate calculations discussed above, we also record allowance for credit losses for specific receivables that are deemed to have a higher risk profile than the rest of the respective pool of receivables, such as concerns about a specific customer going bankrupt and no longer being able to pay the receivables due to us.

Starting in March 2020, we experienced negative impacts to our business due to the disruption caused by Coronavirus Disease 2019 (“COVID-19”). In March 2020, the World Health Organization categorized COVID-19 as a pandemic, and the President of the United States declared the COVID-19 outbreak a national emergency. The Company considered the impact of COVID-19 on the assumptions and estimates used to determine the results reported and asset valuations as of December 31, 2020.

During the year ended December 31, 2020, we increased our loss rates and increased our specific reserves primarily due to the economic disruption caused by COVID-19, which is reflected in our bad debt expense in the current year. This increase was primarily, but not exclusively, due to concern over collectability of receivables from customers more directly impacted by COVID-19.

Activity in our allowance for credit losses consisted of the following (in thousands):


	Year Ended December 31,
	2020
	Service		Construction		Other		Total
Balance at beginning of year	$	3,192	$	3,400	$	315	$	6,907
Impact of new accounting standard		310		331		54		695
Bad debt expense (benefit)		2,566		2,697		(10)		5,253
Deductions for uncollectible receivables written off, net of recoveries		(1,431)		(735)		—		(2,166)
Credit allowance of acquired companies on the acquisition date		—		335		—		335
Reclass to other current liabilities		—		—		(315)		(315)
Balance at December 31, 2020	$	4,637	$	6,028	$	44	$	10,709


	Year Ended December 31,
	2019
Balance at beginning of year	$	5,898
Bad debt expense (benefit)		2,978
Deductions for uncollectible receivables written off, net of recoveries		(3,924)
Credit allowance of acquired companies on the acquisition date		1,955
Balance at December 31, 2019	$	6,907

Inventories

Inventories consist of parts and supplies that we purchase and hold for use in the ordinary course of business and are stated at the lower of cost or net realizable value using the average-cost method.

Property and Equipment

Property and equipment are stated at cost, and depreciation is computed using the straight-line method over the estimated useful lives of the assets. Leasehold improvements are capitalized and amortized over the lesser of the expected life of the lease or the estimated useful life of the asset.

Expenditures for repairs and maintenance are charged to expense when incurred. Expenditures for major renewals and betterments, which extend the useful lives of existing equipment, are capitalized and depreciated over the remaining useful life of the equipment. Upon retirement or disposition of property and equipment, the cost and related accumulated depreciation are removed from the accounts and any resulting gain or loss is recognized in “Gain on sale of assets” in the Statement of Operations.

Recoverability of Goodwill and Identifiable Intangible Assets

Goodwill is the excess of purchase price over the fair value of the net assets of acquired businesses. We assess goodwill for impairment each year, and more frequently if circumstances suggest an impairment may have occurred.

When the carrying value of a given reporting unit exceeds its fair value, a goodwill impairment loss is recorded for this difference, not to exceed the carrying amount of goodwill. The requirements for assessing whether goodwill has been impaired involve market-based information. This information, and its use in assessing goodwill, entails some degree of subjective assessment.

We perform our annual impairment testing as of October 1, and any impairment charges resulting from this process are reported in the fourth quarter. We segregate our operations into reporting units based on the degree of operating and financial independence of each unit and our related management of them. We perform our annual goodwill impairment testing at the reporting unit level. We perform a goodwill impairment review for each of our operating units, as we have determined that each of our operating units are reporting units.

In the evaluation of goodwill for impairment, we have the option to first assess qualitative factors to determine whether the existence of events or circumstances lead to a determination that it is more likely than not that the fair value of one of our reporting units is greater than its carrying value. If, after completing such assessment, we determine it is more likely than not that the fair value of a reporting unit is greater than its carrying amount, then there is no need to perform any further testing. If we conclude otherwise, or if we elect to perform a quantitative assessment, then we calculate the fair value of the reporting unit and compare the fair value with the carrying value of the reporting unit.

We estimate the fair value of the reporting unit based on a market approach and an income approach, which utilizes discounted future cash flows. Assumptions critical to the fair value estimates under the discounted cash flow model include discount rates, cash flow projections, projected long-term growth rates and the determination of terminal values. The market approach utilizes market multiples of invested capital from comparable publicly traded companies (“public company approach”). The market multiples from invested capital include revenue, book equity plus debt and earnings before interest, provision for income taxes, depreciation and amortization (“EBITDA”).

We amortize identifiable intangible assets with finite lives over their useful lives. Changes in strategy and/or market condition may result in adjustments to recorded intangible asset balances or their useful lives.

Long-Lived Assets

Long-lived assets are comprised principally of goodwill, identifiable intangible assets, property and equipment, and deferred tax assets. We periodically evaluate whether events and circumstances have occurred that indicate that the remaining balances of these assets may not be recoverable. We use estimates of future income from operations and cash flows, as well as other economic and business factors, to assess the recoverability of these assets.

Acquisitions

We recognize assets acquired and liabilities assumed in business combinations, including contingent assets and liabilities, based on fair value estimates as of the date of acquisition.

Contingent Consideration—In certain acquisitions, we agree to pay additional amounts to sellers contingent upon achievement by the acquired businesses of certain predetermined profitability targets. We have recognized liabilities for these contingent obligations based on their estimated fair value at the date of acquisition with any differences between the acquisition date fair value and the ultimate settlement of the obligations being recognized in income from operations.

Contingent Assets and Liabilities—Assets and liabilities arising from contingencies are recognized at their acquisition date fair value when their respective fair values are determinable. Acquisition date fair value estimates are revised as necessary if, and when, additional information regarding these contingencies becomes available to further define and quantify assets acquired and liabilities assumed.

Self-Insurance Liabilities

We are substantially self-insured for workers’ compensation, employer’s liability, auto liability, general liability and employee group health claims, in view of the relatively high per-incident deductibles we absorb under our insurance arrangements for these risks. Losses are estimated and accrued based upon known facts, historical trends and industry averages. Estimated losses in excess of our deductible, which have not already been paid, are included in our accrual with a corresponding receivable from our insurance carrier. Loss estimates associated with the larger and longer-developing risks—workers’ compensation, auto liability and general liability—are reviewed by a third-party actuary quarterly. Our self-insurance arrangements are further discussed in Note 13 “Commitments and Contingencies.”

Warranty Costs

We typically warrant labor for the first year after installation on new MEP systems that we build and install, and we pass through to the customer manufacturers’ warranties on equipment. We generally warrant labor for thirty days after servicing existing MEP systems. A reserve for warranty costs is estimated and recorded based upon the historical level of warranty claims and management’s estimate of future costs.

Income Taxes

We conduct business throughout the United States in virtually all fifty states. Our effective tax rate changes based upon our relative profitability, or lack thereof, in states with varying tax rates and rules. In addition, discrete items such as tax law changes, judgments and legal structures can impact our effective tax rate. These items can also include the tax treatment for impairment of goodwill and other intangible assets, changes in fair value of acquisition-related assets and liabilities, tax reserves for uncertain tax positions and accounting for losses associated with underperforming operations.

Income taxes are provided for under the liability method, which takes into account differences between financial statement treatment and tax treatment of certain transactions. Deferred taxes are based on the difference between the financial reporting and tax basis of assets and liabilities. The deferred tax provision represents the change during the reporting period in the deferred tax assets and deferred tax liabilities, net of the effect of acquisitions and dispositions. Deferred tax assets include tax loss and credit carryforwards and are reduced by a valuation allowance if, based on available evidence, it is more-likely-than-not some portion or all of the deferred tax assets will not be realized.

We regularly evaluate valuation allowances established for deferred tax assets for which future realization is uncertain. In assessing the realizability of deferred tax assets, we must consider whether it is more-likely-than-not some portion, or all, of the deferred tax assets will not be realized. We consider all available evidence, both positive and negative, in determining whether a valuation allowance is required. Such evidence includes the scheduled reversal of deferred tax liabilities, projected future taxable income, taxable income in prior carryback years and tax planning strategies in making this assessment, and judgment is required in considering the relative weight of negative and positive evidence.

Significant judgment is required in assessing the timing and amounts of deductible and taxable items. We establish reserves when, despite our belief that our tax return positions are supportable, we believe that certain positions may be disallowed. When facts and circumstances change, we adjust these reserves through our provision for income taxes.

To the extent interest and penalties may be assessed by taxing authorities on any underpayment of income tax, such amounts have been accrued and are classified as a component in provision for income taxes in our Consolidated Statements of Operations.

Concentrations of Credit Risk

We provide services in a broad range of geographic regions. Our credit risk primarily consists of receivables from a variety of customers including general contractors, property owners and developers, and commercial and industrial companies. We are subject to potential credit risk related to changes in business and economic factors throughout the United States within the nonresidential construction industry. However, we are entitled to payment for work performed and have certain lien rights related to that work. Further, we believe that our contract acceptance, billing and collection policies are adequate to manage potential credit risk. We regularly review our accounts receivable and estimate an allowance for uncollectible amounts. We have a diverse customer base, with our top customer representing 5% of consolidated 2020 revenue.

Financial Instruments

Our financial instruments consist of cash and cash equivalents, accounts receivable, other receivables, accounts payable, interest rate swaps, life insurance policies, notes to former owners, a revolving credit facility and a term loan. We believe that the carrying values of these instruments on the accompanying Balance Sheets approximate their fair values.

Insurance Recovery

We recorded a $4.8 million gain in the fourth quarter of 2019 due to insurance proceeds we received in the fourth quarter related to the ransomware incident that occurred in April 2019. Approximately $1.6 million of the gain was recorded as a reduction in SG&A, and the remainder was recorded as a reduction in Cost of Services expense. These proceeds related to recoverable costs that were primarily incurred prior to the fourth quarter in 2019. We do not expect any additional insurance proceeds or other recoveries related to the ransomware incident.

Revenue from Contracts with Customers

12 Months Ended

Dec. 31, 2020

Revenue from Contract with Customers

Revenue from Contracts with Customers

3. Revenue from Contracts with Customers

Revenue is recognized when control of the promised goods or services is transferred to our customers in an amount that reflects the consideration to which we expect to be entitled in exchange for those goods or services. Sales-based taxes are excluded from revenue.

We provide mechanical and electrical contracting services. Our mechanical segment principally includes HVAC, plumbing, piping and controls, as well as off‑site construction, monitoring and fire protection. Our electrical segment includes installation and servicing of electrical systems. We install, maintain, repair and replace products and systems throughout the United States. All of our revenue is recognized over time as we deliver goods and services to our customers. Revenue can be earned based on an agreed upon fixed price or based on actual costs incurred marked up at an agreed upon percentage.

For fixed price agreements, we use the percentage of completion method of accounting under which contract revenue recognizable at any time during the life of a contract is determined by multiplying expected total contract revenue by the percentage of contract costs incurred at any time to total estimated contract costs. More specifically, as part of the negotiation and bidding process to obtain installation contracts, we estimate our contract costs, which include all direct materials, labor and subcontract costs and indirect costs related to contract performance, such as indirect labor, supplies, tools, repairs and depreciation costs. These contract costs are included in our results of operations under the caption “Cost of Services.” Then, as we perform under those contracts, we measure costs incurred, compare them to total estimated costs to complete the contract and recognize a corresponding proportion of contract revenue. Labor costs are considered to be incurred as the work is performed. Subcontractor labor is recognized as the work is performed.

Non‑labor project costs consist of purchased equipment, prefabricated materials and other materials. Purchased equipment on our projects is substantially produced to job specifications and is a value-added element to our work. The costs are considered to be incurred when title is transferred to us, which typically is upon delivery to the work site. Prefabricated materials, such as ductwork and piping, are generally performed at our shops and recognized as contract costs when fabricated for the unique specifications of the job. Other materials costs are generally recorded when delivered to the work site. This measurement and comparison process requires updates to the estimate of total costs to complete the contract, and these updates may include subjective assessments and judgments.

We account for a contract when: (i) it has approval and commitment from both parties, (ii) the rights of the parties are identified, (iii) payment terms are identified, (iv) the contract has commercial substance, and (v) collectability of consideration is probable. We consider the start of a project to be when the above criteria have been met and we either have written authorization from the customer to proceed or an executed contract.

Selling, marketing and estimation costs incurred in relation to selling contracts are expensed as incurred. On rare occasions, we may incur significant expenses related to selling a contract that we only incurred because we sold that contract. If this occurs, we capitalize that cost and amortize it on a percentage of completion basis over the life of the contract. We do not currently have any capitalized selling, marketing, or estimation costs on our Balance Sheet and did not incur any impairment loss in the current year.

We generally do not incur significant incremental costs related to obtaining or fulfilling a contract prior to the start of a project. On rare occasions, when significant pre-contract costs are incurred, they are capitalized and amortized on a percentage of completion basis over the life of the contract. We do not currently have any capitalized obtainment or fulfillment costs on our Balance Sheet and did not incur any impairment loss on such costs in the current year.

Project contracts typically provide for a schedule of billings or invoices to the customer based on our job-to-date percentage of completion of specific tasks inherent in the fulfillment of our performance obligation(s). The schedules for such billings usually do not precisely match the schedule on which costs are incurred. As a result, contract revenue recognized in our Statement of Operations can and usually does differ from amounts that can be billed or invoiced to the customer at any point during the contract. Amounts by which cumulative contract revenue recognized on a contract as of a given date exceed cumulative billings and unbilled receivables to the customer under the contract are reflected as a current asset in our Balance Sheet under the caption “Costs and estimated earnings in excess of billings.” Amounts by which cumulative billings to the customer under a contract as of a given date exceed cumulative contract revenue recognized on the contract are reflected as a current liability in our Balance Sheet under the caption “Billings in excess of costs and estimated earnings.”

Contracts in progress are as follows (in thousands):


	December 31,
	2020		2019
Costs incurred on contracts in progress	$	3,103,580	$	2,518,581
Estimated earnings, net of losses		548,435		405,891
Less—Billings to date		(3,813,171)		(3,033,112)
Less—Unbilled accounts receivable		(45,596)		(55,542)
Less—Unbilled accounts receivable credit allowance		(784)		—
	$	(207,536)	$	(164,182)

Costs and estimated earnings in excess of billings	$	18,622	$	2,736
Plus—Costs and estimated earnings in excess of billings credit allowance		79		—
Billings in excess of costs and estimated earnings		(226,237)		(166,918)
	$	(207,536)	$	(164,182)

Accounts receivable include amounts billed to customers under retention or retainage provisions in construction contracts. Such provisions are standard in our industry and usually allow for a small portion of progress billings or the contract price to be withheld by the customer until after we have completed work on the project, typically for a period of six months. Based on our experience with similar contracts in recent years, the majority of our billings for such retention balances at each Balance Sheet date are finalized and collected within the subsequent year. Retention balances at

December 31, 2020 and 2019 were $124.1 million and $111.7 million, respectively, and are included in accounts receivable.

Accounts payable at December 31, 2020 and 2019 included $22.2 million and $15.8 million of retainage under terms of contracts with subcontractors, respectively. The majority of the retention balances at each Balance Sheet date are finalized and paid within the subsequent year.

The percentage of completion method of accounting is also affected by changes in job performance, job conditions, and final contract settlements. These factors may result in revisions to estimated costs and, therefore, revenue. Such revisions are frequently based on further estimates and subjective assessments. The effects of these revisions are recognized in the period in which revisions are determined. When such revisions lead to a conclusion that a loss will be recognized on a contract, the full amount of the estimated ultimate loss is recognized in the period such conclusion is reached, regardless of the percentage of completion of the contract.

Revisions to project costs and conditions can give rise to change orders under which there is an agreement between the customer and us that the customer pays an additional or reduced contract price. Revisions can also result in claims we might make against the customer to recover project variances that have not been satisfactorily addressed through change orders with the customer. Except in certain circumstances, we do not recognize revenue or margin based on change orders or claims until they have been agreed upon with the customer. The amount of revenue associated with unapproved change orders and claims was immaterial for the year ended December 31, 2020.

Variations from estimated project costs could have a significant impact on our operating results, depending on project size, and the recoverability of the variation via additional customer payments.

We typically invoice our customers with payment terms of net due in 30 days. It is common in the construction industry for a contract to specify more lenient payment terms allowing the customer 45 to 60 days to make their payment. It is also common for the contract in the construction industry to specify that a general contractor is not required to submit payments to a subcontractor until it has received those funds from the owner or funding source. In most instances, we receive payment of our invoices between 30 to 90 days of the date of the invoice.

A performance obligation is a promise in a contract to transfer a distinct good or service to the customer. A contract’s transaction price is allocated to each distinct performance obligation and recognized as revenue when, or as, the performance obligation is satisfied.

To determine the proper revenue recognition method for contracts, we evaluate whether two or more contracts should be combined and accounted for as one performance obligation and whether the combined or single contract should be accounted for as more than one performance obligation. This evaluation requires significant judgment and the decision to combine a group of contracts or separate the combined or single contract into multiple performance obligations could change the amount of revenue and profit recorded in a given period. For most of our contracts, the customer contracts with us to provide a significant service of integrating a complex set of tasks and components into a single project or capability (even if that single project results in the delivery of multiple units). Hence, the entire contract is accounted for as one performance obligation. Less commonly, however, we may promise to provide distinct goods or services within a contract, in which case we separate the contract into more than one performance obligation. If a contract is separated into more than one performance obligation, we allocate the total transaction price to each performance obligation in an amount based on the estimated relative standalone selling prices of the promised goods or services underlying each performance obligation. We infrequently sell standard products with observable standalone sales. In such cases, the observable standalone sales are used to determine the standalone selling price. More frequently, we sell a customized, customer-specific solution, and, in these cases, we typically use the expected cost plus a margin approach to estimate the standalone selling price of each performance obligation.

We recognize revenue over time for all of our services as we perform them because (i) control continuously transfers to that customer as work progresses, and (ii) we have the right to bill the customer as costs are incurred. The customer typically controls the work in process, as evidenced either by contractual termination clauses or by our rights to payment for work performed to date plus a reasonable profit to deliver products or services that do not have an alternative use to the Company.

In our mechanical segment, for a small portion of our business in which our services are delivered in the form of service maintenance agreements for existing systems to be repaired and maintained, as opposed to constructed, our performance obligation is to maintain the customer’s mechanical system for a specific period of time. Similar to jobs, we recognize revenue over time; however, for service maintenance agreements in which the full cost to provide services may not be known, we generally use an input method to recognize revenue, which is based on the amount of time we have provided our services out of the total time we have been contracted to perform those services.

Due to the nature of the work required to be performed on many of our performance obligations, the estimation of total revenue and cost at completion (the process described below in more detail) is complex, subject to many variables and requires significant judgment. The consideration to which we are entitled on our long-term contracts may include both fixed and variable amounts. Variable amounts can either increase or decrease the transaction price. A common example of variable amounts that can either increase or decrease contract value are pending change orders that represent contract modifications for which a change in scope has been authorized or acknowledged by our customer, but the final adjustment to contract price is yet to be negotiated. Other examples of positive variable revenue include amounts awarded upon achievement of certain performance metrics, program milestones or cost of completion date targets and can be based upon customer discretion. Variable amounts can result in a deduction from contract revenue if we fail to meet stated performance requirements, such as complying with the construction schedule.

Contracts are often modified to account for changes in contract specifications and requirements. We consider contract modifications to exist when the modification either creates new or changes the existing enforceable rights and obligations. Most of our contract modifications are for goods or services that are not distinct from the existing performance obligation(s). The effect of a contract modification on the transaction price, and our measure of progress for the performance obligation to which it relates, is recognized as an adjustment to revenue (either as an increase or decrease) on a cumulative catchup basis.

We have a Company-wide policy requiring periodic review of the Estimate at Completion in which management reviews the progress and execution of our performance obligations and estimated remaining obligations. As part of this process, management reviews information including, but not limited to, any outstanding key contract matters, progress towards completion and the related program schedule, identified risks and opportunities and the related changes in estimates of revenue and costs. The risks and opportunities include management's judgment about the ability and cost to achieve the schedule (e.g., the number and type of milestone events), technical requirements (e.g., a newly developed product versus a mature product) and other contract requirements. Management must make assumptions and estimates regarding labor productivity and availability, the complexity of the work to be performed, the availability of materials, the length of time to complete the performance obligation (e.g., to estimate increases in wages and prices for materials and related support cost allocations), execution by our subcontractors, the availability and timing of funding from our customer, and overhead cost rates, among other variables.

Based on this analysis, any adjustments to revenue, cost of services, and the related impact to operating income are recognized as necessary in the quarter when they become known. These adjustments may result from positive program performance if we determine we will be successful in mitigating risks surrounding the technical, schedule and cost aspects of those performance obligations or realizing related opportunities and may result in an increase in operating income during the performance of individual performance obligations. Likewise, if we determine we will not be successful in mitigating these risks or realizing related opportunities, these adjustments may result in a decrease in operating income. Changes in estimates of revenue, cost of services and the related impact to operating income are recognized quarterly on a cumulative catchup basis, meaning we recognize in the current period the cumulative effect of the changes on current and prior periods based on a performance obligation's percentage of completion. A significant change in one or more of these estimates could affect the profitability of one or more of our performance obligations. For projects in which estimates of total costs to be incurred on a performance obligation exceed total estimates of revenue to be earned, a provision for the entire loss on the performance obligation is recognized in the period the loss is determined.

The Company typically does not incur any returns, refunds, or similar obligations after the completion of the performance obligation since any deficiencies are corrected during the course of the work or are included as a modification to revenue. The Company does offer an industry standard warranty on our work, which is most commonly for a one-year period. The vendors providing the equipment and materials are responsible for any failures in their product unless installed incorrectly. We include an estimated amount to cover estimated warranty expense in our Cost of Services and record a liability on our Balance Sheet to cover our current estimated outstanding warranty obligations.

During the years ended December 31, 2020 and December 31, 2019, net revenue recognized from our performance obligations satisfied in previous periods was not material.

Disaggregation of Revenue

Our consolidated 2020 revenue was derived from contracts to provide service activities in the mechanical and electrical services segments we serve. Refer to Note 16 “Segment Information” for additional information on our reportable segments. We disaggregate our revenue from contracts with customers by activity, customer type and service provided, as we believe it best depicts how the nature, amount, timing and uncertainty of our revenue and cash flows are affected by economic factors. See details in the following tables (dollars in thousands):


	Year Ended December 31,
Revenue by Service Provided	2020				2019				2018
Mechanical Services	$	2,413,016	84.5	%	$	2,251,560	86.1	%	$	2,176,223	99.7	%
Electrical Services		443,643	15.5	%		363,717	13.9	%		6,656	0.3	%
Total	$	2,856,659	100.0	%	$	2,615,277	100.0	%	$	2,182,879	100.0	%

	Year Ended December 31,
Revenue by Type of Customer	2020				2019				2018
Industrial	$	1,112,075	38.9	%	$	886,668	33.9	%	$	596,557	27.3	%
Education		487,922	17.1	%		412,318	15.8	%		391,937	18.0	%
Office Buildings		319,426	11.2	%		348,640	13.3	%		288,090	13.2	%
Healthcare		371,105	13.0	%		358,155	13.7	%		319,958	14.7	%
Government		163,717	5.7	%		162,507	6.2	%		143,958	6.6	%
Retail, Restaurants and Entertainment		239,541	8.4	%		248,083	9.5	%		225,348	10.3	%
Multi-Family and Residential		86,799	3.0	%		104,693	4.0	%		136,075	6.2	%
Other		76,074	2.7	%		94,213	3.6	%		80,956	3.7	%
Total	$	2,856,659	100.0	%	$	2,615,277	100.0	%	$	2,182,879	100.0	%

	Year Ended December 31,
Revenue by Activity Type	2020				2019				2018
New Construction	$	1,333,739	46.7	%	$	1,201,122	45.9	%	$	829,978	38.0	%
Existing Building Construction		910,807	31.9	%		793,159	30.3	%		796,946	36.5	%
Service Projects		241,402	8.4	%		231,228	8.9	%		206,506	9.5	%
Service Calls, Maintenance and Monitoring		370,711	13.0	%		389,768	14.9	%		349,449	16.0	%
Total	$	2,856,659	100.0	%	$	2,615,277	100.0	%	$	2,182,879	100.0	%

Contract Assets and Liabilities

Contract assets include unbilled amounts typically resulting from sales under long term contracts when the cost to cost method of revenue recognition is used, revenue recognized exceeds the amount billed to the customer and right to payment is conditional, subject to completing a milestone, such as a phase of the project. Contract assets are generally classified as current.

Contract liabilities consist of advance payments and billings in excess of revenue recognized. Our contract assets and liabilities are reported in a net position on a contract by contract basis at the end of each reporting period. We classify advance payments and billings in excess of revenue recognized as current. It is very unusual for us to have advanced payments with a term of greater than one year; therefore, our contract assets and liabilities are usually all

current. If we have advanced payments with a term greater than one year, the noncurrent portion of advanced payments would be included in other long-term liabilities in our consolidated Balance Sheets.

The following table presents the changes in contract assets and contract liabilities (in thousands):


	Year Ended December 31,					Year Ended December 31,
	2020				2019
	Contract		Contract		Contract		Contract
	Assets		Liabilities		Assets		Liabilities
Balance at beginning of period	$	2,736	$	166,918	$	10,213	$	130,986
Change due to acquisitions / disposals		9,509		39,885		6,573		31,556
Change related to credit allowance		(79)		—		—		—
Other changes in the period		6,456		19,434		(14,050)		4,376
Balance at end of period	$	18,622	$	226,237	$	2,736	$	166,918

During the years ended December 31, 2020 and 2019, we recognized revenue of $165.8 million and $126.7 million related to our contract liabilities at January 1, 2020 and January 1, 2019, respectively.

We did not have any impairment losses recognized on our receivables or contract assets in 2020 and 2019.

Remaining Performance Obligations

Remaining construction performance obligations represent the remaining transaction price of firm orders for which work has not been performed and exclude unexercised contract options. As of December 31, 2020, the aggregate amount of the transaction price allocated to remaining performance obligations was $1.51 billion. The Company expects to recognize revenue on approximately 80-85% of the remaining performance obligations over the next 12 months, with the remaining recognized thereafter. Our service maintenance agreements are generally one-year renewable agreements. We have adopted the practical expedient that allows us to not include service maintenance contracts with a term of less than one year; therefore, we do not report unfulfilled performance obligations for service maintenance agreements.

- Definition

The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-URI http://asc.fasb.org/topic&trid=49130388

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130551-203045

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130556-203045

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130550-203045

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130558-203045

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

+ Details

Fair Value Measurements

12 Months Ended

Dec. 31, 2020

Fair Value Measurements

Fair Value Measurements

4. Fair Value Measurements

Interest Rate Risk Management and Derivative Instruments

In April 2020, we entered into interest rate swap agreements to reduce our exposure to variable interest rates on our term loan and revolving credit facility. The notional amount covered by these interest rate swaps was $130.0 million as of December 31, 2020 and decreases to $80.0 million by November 30, 2021 until the termination date of September 30, 2022.

We use derivative instruments to manage exposure to market risk, including interest rate risk. All of our current derivatives are designated and accounted for as economic hedges. Unsettled amounts under our economic hedges are recorded on the Balance Sheet at fair value in “Other Receivables” or “Other Current Liabilities.” Gains and losses on our interest rate swaps are recorded on the Income Statement in “Interest Expense.” For the year ended December 31, 2020, we recognized a net loss of $0.3 million related to our interest rate swaps. We currently do not have any derivatives that are accounted for as hedges under ASC 815.

Fair Value Measurement

We classify and disclose assets and liabilities carried at fair value in one of the following three categories:

●

Level 1—quoted prices in active markets for identical assets and liabilities;

●

Level 2—observable market-based inputs or unobservable inputs that are corroborated by market data; and

●

Level 3—significant unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions.

The following table summarizes the fair values, and levels within the fair value hierarchy in which the fair value measurements fall, for assets and liabilities measured on a recurring basis as of December 31, 2020 and 2019 (in thousands):


	Fair Value Measurements at December 31, 2020
	Level 1		Level 2		Level 3		Total
Cash and cash equivalents	$	54,896	$	—	$	—	$	54,896
Life insurance—cash surrender value	$	—	$	5,420	$	—	$	5,420
Contingent earn-out obligations	$	—	$	—	$	25,979	$	25,979
Interest rate swap liability	$	—	$	42	$	—	$	42

	Fair Value Measurements at December 31, 2019
	Level 1		Level 2		Level 3		Total
Cash and cash equivalents	$	50,788	$	—	$	—	$	50,788
Life insurance—cash surrender value	$	—	$	3,905	$	—	$	3,905
Contingent earn-out obligations	$	—	$	—	$	28,497	$	28,497

Cash and cash equivalents consist primarily of highly rated money market funds at a variety of well-known institutions with original maturities of three months or less. The original cost of these assets approximates fair value due to their short-term maturity. The Company’s outstanding term loan held by third-party financial institutions is carried at cost, adjusted for debt issuance costs. The Company’s term loan is not publicly traded and the carrying amount approximates fair value as the loan accrues interest at a variable rate. The carrying value of our borrowings associated with the Revolving Credit Facility approximate its fair value due to the variable rate on such debt.

We have life insurance policies covering 86 employees with a combined face value of $61.7 million. The policies are invested in several investment vehicles, and the fair value measurement of the cash surrender balance associated with these policies is determined using Level 2 inputs within the fair value hierarchy and will vary with investment performance. The cash surrender value of these policies was $5.4 million as of December 31, 2020 and $3.9 million as of December 31, 2019. These assets are included in “Other Noncurrent Assets” in our consolidated Balance Sheets.

We value contingent earn-out obligations using a probability weighted discounted cash flow method. This fair value measurement is based on significant unobservable inputs in the market and thus represents a Level 3 measurement within the fair value hierarchy. This analysis reflects the contractual terms of the purchase agreements (e.g., minimum and maximum payments, length of earn-out periods, manner of calculating any amounts due, etc.) and utilizes assumptions with regard to future cash flows, probabilities of achieving such future cash flows and a discount rate. The contingent earn-out obligations are measured at fair value each reporting period and changes in estimates of fair value are recognized in earnings. Significant unobservable inputs that could impact the fair value measurement include our weighted average cost of capital and the forecasted level of operating income for each earn-out measurement. As of December 31, 2020, cash flows were discounted using a weighted average cost of capital ranging from 9.5% - 17.0%.

The table below presents a reconciliation of the fair value of our contingent earn-out obligations that use significant unobservable inputs (Level 3) (in thousands):


	December 31,
	2020		2019
Balance at beginning of year	$	28,497	$	7,375
Issuances		16,715		19,500
Settlements		(10,114)		(1,369)
Adjustments to fair value		(9,119)		2,991
Balance at end of year	$	25,979	$	28,497

The fair value for our interest rate swaps is based upon inputs corroborated by observable market data with similar tenors, which are considered Level 2 inputs. The Company’s outstanding term loan held by third-party financial institutions is carried at cost, adjusted for debt issuance costs. The Company’s term loan is not publicly traded and the carrying amount approximates fair value as the loan accrues interest at a variable rate. The carrying value of our borrowings associated with the revolving credit facility approximate its fair value due to the variable rate on such debt.

We measure certain assets at fair value on a nonrecurring basis. These assets are recognized at fair value when they are deemed to be other-than-temporarily impaired. No goodwill or other intangible asset impairments were recorded during the years ended December 31, 2020, 2019 and 2018. We did not recognize any other impairments on those assets required to be measured at fair value on a nonrecurring basis. See Note 6 “Goodwill and Identifiable Intangible Assets, Net” for further discussion.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Acquisitions

12 Months Ended

Dec. 31, 2020

Acquisitions

Acquisitions

5. Acquisitions

TAS Energy Inc. Acquisition

On April 1, 2020, we consummated a merger through which TAS Energy Inc. (“TAS”) became a wholly owned subsidiary of the Company. TAS is headquartered in Houston, Texas, and is a leading engineering, design and construction provider of modular construction systems serving the technology, power and industrial sectors. As a result of the acquisition, TAS is a wholly owned subsidiary of the Company reported in our mechanical services segment. Revenue attributable to TAS was $106.4 million for the nine months from the acquisition date.

The following summarizes the acquisition date fair value of consideration transferred and the acquisition date fair value of the identifiable assets acquired and liabilities assumed, including an amount for goodwill (in thousands):


Consideration transferred:
Cash paid at closing	$	105,950
Working capital adjustment		40,455
Notes issued to former owners		14,000
Estimated fair value of contingent earn-out payments		9,100
	$	169,505
Recognized amounts of identifiable assets acquired and liabilities assumed:
Cash and cash equivalents	$	47,460
Billed and unbilled accounts receivable		18,702
Other current assets		15,634
Other long-term assets		1,556
Property and equipment		7,709
Goodwill		72,788
Identifiable intangible assets		53,400
Lease right-of-use asset		19,736
Accounts payable		(16,453)
Billings in excess of costs and estimated earnings		(24,196)
Current lease liabilities		(2,337)
Accrued expenses and other current liabilities		(4,109)
Long-term lease liabilities		(17,398)
Other long-term liabilities		(2,987)
	$	169,505

The allocation of the purchase price to the assets acquired and liabilities assumed is preliminary and, therefore, subject to change pending the completion of the final valuation of intangible assets and accrued liabilities. Goodwill represents the future economic benefits arising from other assets acquired that could not be individually identified and separately recognized. The goodwill recognized as a result of the TAS acquisition is not deductible for tax purposes.

In estimating the fair value of the acquired intangible assets, we utilized the valuation methodology determined to be the most appropriate for the individual intangible asset. In order to estimate the fair value of the backlog and customer relationships, we utilized an excess earnings methodology, which consisted of the projected cash flows attributable to these assets discounted to present value using a risk-adjusted discount rate that represented the required rate of return. The trade name value was determined based on the relief-from-royalty method, which applies a royalty rate to the revenue stream attributable to this asset, and the resulting royalty payment is tax effected and discounted to present value. Some of the more significant estimates and assumptions inherent in determining the fair value of the identifiable intangible assets are associated with forecasting cash flows and profitability, which represent Level 3 inputs.

The primary assumptions used were generally based upon the present value of anticipated cash flows discounted at rates ranging from 15% - 23.5%. Estimated years of projected earnings generally follow the range of estimated remaining useful lives for each intangible asset class.

As a result of the TAS acquisition, we acquired $53.2 million of federal net operating loss (“NOL”) carryforwards and $6.5 million of state NOL carryforwards. Our ability to utilize these NOL carryforwards to reduce taxable income in future years is subject to significant limitations under Section 382 of the Internal Revenue Code (the “Code”) due to the ownership change in TAS on April 1, 2020. While we expect to fully utilize the federal NOL carryforwards before they begin to expire in 2031, a full valuation allowance was recorded against virtually all of the state NOL carryforwards. We do not believe it is more-likely-than-not that TAS will have sufficient revenue-generating operations in those states in the future.

The acquired intangible assets include the following (dollars in thousands):


	Valuation Method	Estimated Useful Life		Estimated Fair Value
Backlog	Excess earnings	1 year	$	5,200
Trade Name	Relief-from-royalty	25 years		8,200
Customer Relationships	Excess earnings	10 years		40,000
Total			$	53,400

The contingent earn-out obligation is associated with the achievement of specified earnings milestones over a 27-month period, and the range of estimated milestone payments is from $1 million to $8 million. We determined the initial fair value of the contingent earn-out obligation based on the Monte Carlo Simulation method, which represents a Level 3 measurement. Cash flows were discounted using a 17.7% discount rate, which we believe is appropriate and representative of a market participant assumption. Subsequent to the acquisition date, the contingent earn-out obligation is re-measured at fair value each reporting period. Changes in the estimated fair value of the contingent payments subsequent to the acquisition date are recognized immediately in earnings.

T E C Industrial Construction and Maintenance Acquisition

On December 31, 2020, we consummated an acquisition of all outstanding equity interests of Tennessee Electric Company, Inc. dba TEC Industrial Maintenance and Construction (“T E C”). T E C is headquartered in Kingsport, Tennessee, and provides multidisciplined construction and industrial services, including electrical, mechanical and other plant services, primarily in Tennessee and surrounding states. As a result of the acquisition, T E C is a wholly owned subsidiary of the Company reported in our electrical services segment. T E C did not contribute to our revenue in 2020.


Consideration transferred:
Cash paid at closing	$	73,000
Working capital adjustment		2,006
Notes issued to former owners		7,000
Estimated fair value of contingent earn-out payments		7,560
	$	89,566
Recognized amounts of identifiable assets acquired and liabilities assumed:
Cash and cash equivalents	$	4
Billed and unbilled accounts receivable		13,660
Costs in excess of billings		2,040
Other current assets		108
Other long-term assets		53
Property and equipment		912
Goodwill		44,431
Identifiable intangible assets		37,200
Lease right-of-use asset		1,234
Accounts payable		(4,123)
Billings in excess of costs and estimated earnings		(2,838)
Current lease liabilities		(175)
Accrued expenses and other current liabilities		(1,881)
Long-term lease liabilities		(1,059)
	$	89,566

The allocation of the purchase price to the assets acquired and liabilities assumed is preliminary and, therefore, subject to change pending the completion of the final valuation of identifiable assets acquired and liabilities assumed. Goodwill represents the future economic benefits arising from other assets acquired that could not be individually identified and separately recognized. All of the goodwill recognized as a result of the T E C acquisition is tax deductible.

The acquired intangible assets include the following (dollars in thousands):


	Valuation	Estimated	Estimated
	Method	Useful Life	Fair Value
Backlog	Excess earnings	2 years	$	7,200
Trade Name	Relief-from-royalty	20 years		5,800
Customer Relationships	Excess earnings	9 years		24,200
Total			$	37,200

The contingent earn-out obligation is associated with the achievement of specified earnings milestones over a three year period, and the range of estimated milestone payments is from less than $1 million to $5 million. We determined the initial fair value of the contingent earn-out obligation based on the Monte Carlo Simulation method, which represents a Level 3 measurement. Cash flows were discounted using a 12.9% discount rate, which we believe is appropriate and representative of a market participant assumption. Subsequent to the acquisition date, the contingent earn-out obligation is re-measured at fair value each reporting period. Changes in the estimated fair value of the contingent payments subsequent to the acquisition date are recognized immediately in earnings.

Other Acquisitions

In addition to the TAS and T E C acquisitions, we completed the acquisition of an electrical contractor in North Carolina in the first quarter of 2020 with a total purchase price of $41.6 million. This acquisition is reported in our electrical services segment.

In the second quarter of 2019, we acquired all of the issued and outstanding stock of Walker TX Holding Company, LLC and each of its wholly owned subsidiaries (collectively “Walker”) for $235.4 million of which $187.0 million was allocated to goodwill and identifiable intangible assets. The total purchase price included $178.0 million in cash, $25.0 million in notes payable to former owners, a $20.5 million advance to former owners, a $19.5 million contingent earn-out obligation and a $0.2 million tax equalization payment, offset by a $7.8 million working capital adjustment. Walker is a full-service electrical contracting and network infrastructure engineering business serving commercial and industrial clients with headquarters in Irving, Texas, and operations throughout the state of Texas. As a result of the acquisition, Walker is a wholly owned subsidiary of the Company reported in our electrical services segment. In addition to the Walker acquisition, we completed two additional acquisitions in 2019 which were “tucked-in” with existing operations. The total purchase price for these additional acquisitions, including earn-outs, was $2.6 million.

The results of operations of acquisitions are included in our consolidated financial statements from their respective acquisition dates. Our consolidated Balance Sheet includes preliminary allocations of the purchase price to the assets acquired and liabilities assumed for the applicable acquisitions pending the completion of the final valuation of intangible assets and accrued liabilities. Excluding the Walker and TAS acquisitions, the acquisitions completed in 2020 and the prior year were not material, individually or in the aggregate. Additional contingent purchase price (“earn-out”) has been or will be paid if certain acquisitions achieve predetermined profitability targets. Such earn-outs, when they are not subject to the continued employment of the sellers, are estimated as of the purchase date and included as part of the consideration paid for the acquisition. If we have an earn-out under which continued employment is a condition to receipt of payment, then the earn-out is recorded as compensation expense over the period earned.

Goodwill and Identifiable Intangible Assets, Net

12 Months Ended

Dec. 31, 2020

Goodwill and Identifiable Intangible Assets, Net

Goodwill and Identifiable Intangible Assets, Net

6. Goodwill and Identifiable Intangible Assets, Net

Goodwill

The changes in the carrying amount of goodwill are as follows (in thousands):


	Mechanical Services		Electrical Services
	Segment		Segment		Total
Balance at December 31, 2018	$	235,182	$	—	$	235,182
Acquisitions and purchase price adjustments (See Note 5)		579		96,686		97,265
Impact of segment reorganization		(1,101)		1,101		—
Balance at December 31, 2019		234,660		97,787		332,447
Acquisitions and purchase price adjustments (See Note 5)		72,788		59,157		131,945
Balance at December 31, 2020	$	307,448	$	156,944	$	464,392

The aggregate goodwill balance as of December 31, 2020 and 2019 includes $116.6 million of accumulated impairment charges, all of which relate to the mechanical services segment.

We perform our annual impairment testing on October 1, or more frequently, if events and circumstances indicate impairment may have occurred. As discussed in Note 2, “Summary of Significant Accounting Policies,” we have the option to first perform a qualitative assessment to determine whether it is more likely than not that the fair value of the reporting unit is less than the carrying value.

During our annual impairment testing on October 1, 2019, we performed a quantitative assessment where the fair value of each reporting unit was estimated using a discounted cash flow model combined with a market valuation approach. We assigned a weighting of 50% to the discounted cash flow analysis and 50% to the public company approach for the year ended December 31, 2019. Based on this assessment, we concluded that the fair value of each of the reporting units was greater than its carrying value. The calculated fair values for the majority of the Company’s reporting units that have goodwill were significantly in excess (all greater than 80%) of the respective reporting unit’s carrying value, while two reporting units that were recently acquired had calculated fair values in excess of carrying value of at least 27%.

During our annual impairment testing on October 1, 2020, we performed a qualitative assessment for all of our reporting units except one, which considered various factors, including changes in the carrying value of the reporting unit, forecasted operating results, long-term growth rates and discount rates. Additionally, we considered qualitative key events and circumstances (i.e. macroeconomic environment, industry and market specific conditions, cost factors and events specific to the reporting unit, etc.). Based on this assessment, we concluded that it was more likely than not that the fair value of each of the reporting units was greater than its carrying value. Accordingly, no further testing was required. For Walker, we performed a step 1 quantitative assessment and the calculated fair value exceeded the carrying value by 24%. As a result of uncertainty caused by COVID-19 and Walker’s smaller excess of fair value percentage, this reporting unit is more susceptible to impairment risk from additional adverse changes in its operating environment, including micro- and macroeconomic environment conditions that could negatively impact them. Such adverse changes could include worsening economic conditions in the locations or markets they primarily serve, whether due to COVID-19 or other events and conditions. As of December 31, 2020, Walker had a goodwill balance of $96.8 million.

There are significant inherent uncertainties and management judgment involved in estimating the fair value of each reporting unit. While we believe we have made reasonable estimates and assumptions to estimate the fair value of our reporting units, it is possible that a material change could occur. If actual results are not consistent with our current estimates and assumptions, or the current economic outlook worsens, goodwill impairment charges may be recorded in future periods.

Identifiable Intangible Assets, Net

Identifiable intangible assets consist of the following (dollars in thousands):


	Weighted-Average	December 31, 2020				December 31, 2019
	Remaining Useful Lives	Gross Book		Accumulated		Gross Book		Accumulated
	in Years	Value		Amortization		Value		Amortization
Customer Relationships	8.0	$	255,692	$	(103,919)	$	183,061	$	(80,813)
Backlog	2.0		19,800		(12,600)		7,400		(6,388)
Trade Names	20.5		91,495		(18,661)		71,995		(15,281)
Total	11.7	$	366,987	$	(135,180)	$	262,456	$	(102,482)

The amounts attributable to customer relationships and tradenames are amortized to “Selling, General and Administrative Expenses” based upon the estimated consumption of their economic benefits, or a straight-line method over periods from one to twenty-five years if the pattern of economic benefit cannot otherwise be reliably estimated. The amounts attributable to backlog are being amortized to “Cost of Services” on a proportionate method over the remaining backlog period. Amortization expense for the years ended December 31, 2020, 2019 and 2018 was $32.7 million, $27.1 million and $20.1 million, respectively.

As of December 31, 2020, future amortization expense of identifiable intangible assets was as follows (in thousands):


Year ended December 31—
2021	$	32,344
2022		27,412
2023		23,514
2024		22,164
2025		19,977
Thereafter		106,396
Total	$	231,807

Property and Equipment

12 Months Ended

Dec. 31, 2020

Property and Equipment

Property and Equipment

7. Property and Equipment

Property and equipment consist of the following (dollars in thousands):


	Estimated
	Useful Lives	December 31,
	in Years	2020		2019
Land	—	$	7,167	$	6,206
Transportation equipment	1 - 7		113,802		106,972
Machinery and equipment	1 - 20		43,386		35,575
Computer and telephone equipment	1 - 10		23,215		20,744
Buildings and leasehold improvements	1 - 40		69,683		62,301
Furniture and fixtures	1 - 17		5,861		5,244
Construction in progress	—		1,294		2,123
			264,408		239,165
Less—Accumulated depreciation			(147,202)		(129,369)
Property and equipment, net		$	117,206	$	109,796

Depreciation expense for the years ended December 31, 2020, 2019 and 2018 was $27.9 million, $24.5 million and $22.6 million, respectively.

Detail of Other Current Liabilities

12 Months Ended

Dec. 31, 2020

Detail of Other Current Liabilities

Detail of Other Current Liabilities

8. Detail of Other Current Liabilities

Other current liabilities consist of the following (in thousands):


	December 31,
	2020		2019
Accrued warranty costs	$	8,914	$	7,452
Current lease liability		16,586		14,016
Accrued job losses		2,151		2,226
Accrued sales and use tax		3,731		2,938
Deferred revenue		4,559		5,506
Liabilities due to former owners		10,280		11,219
Other current liabilities		45,271		38,273
	$	91,492	$	81,630

Debt Obligations

12 Months Ended

Dec. 31, 2020

Debt Obligations

Debt Obligations

9. Debt Obligations

Debt obligations consist of the following (in thousands):


	December 31,
	2020		2019
Revolving credit facility	$	70,000	$	28,000
Term loan		135,000		150,000
Notes to former owners		31,000		48,483
Total principal amount		236,000		226,483
Less—unamortized debt issuance costs		(267)		(348)
Total debt, net of unamortized debt issuance costs		235,733		226,135
Less—current portion		—		(20,817)
Total long-term portion of debt, net	$	235,733	$	205,318

At December 31, 2020, future principal payments of debt are as follows (in thousands):


Year ended December 31—
2021	$	—
2022		23,000
2023		34,000
2024		26,500
2025		152,500
Thereafter		—
	$	236,000

Interest expense included the following primary elements (in thousands):


	Year Ended December 31,
	2020		2019		2018
Interest expense on notes to former owners	$	1,354	$	1,531	$	642
Interest expense on borrowings and unused commitment fees		5,319		6,887		2,211
Interest expense on interest rate swaps		338		—		—
Letter of credit fees		830		512		474
Amortization of debt financing costs		544		387		383
Total	$	8,385	$	9,317	$	3,710

Revolving Credit Facility and Term Loan

In December 2019, we amended our senior credit facility (the “Facility”) provided by a syndicate of banks, increasing our borrowing capacity from $400.0 million to $600.0 million. As amended, the Facility is composed of a revolving credit line in the amount of $450.0 million and a $150.0 million term loan, and the Facility also provides for a $150.0 million accordion or increase option for the revolving portion of the Facility. As of December 31, 2020, the Facility capacity was $585.0 million as the term loan was paid down by $15.0 million since the inception of the Facility. The amended Facility also includes a sublimit of up to $160.0 million issuable in the form of letters of credit. The Facility expires in January 2025 and is secured by a first lien on substantially all of our personal property except for assets related to projects subject to surety bonds and assets held by certain unrestricted subsidiaries and our wholly owned captive insurance company, and a second lien on our assets related to projects subject to surety bonds. In 2019, we incurred approximately $1.4 million in financing and professional costs in connection with an amendment to the Facility which are being amortized over the remaining term of the Facility. Of this amount, $0.4 million is attributable to the term loan and is being amortized using the effective interest method. The remaining $1.0 million is attributable to the revolving credit line, which combined with the previous unamortized costs of $1.3 million, is being amortized over the remaining term of the Facility on a straight-line basis as a non-cash charge to interest expense. For the term loan, we are required to make quarterly payments increasing over time from 1.25% to 3.75% of the original aggregate principal amount of the term loan, with the balance due in January 2025. As of December 31, 2020, we had $135.0 million

principal outstanding on the term loan, $70.0 million of outstanding borrowings on the revolving credit facility, $49.5 million in letters of credit outstanding and $330.5 million of credit available.

Collateral

A common practice in our industry is the posting of payment and performance bonds with customers. These bonds are offered by financial institutions known as sureties and provide assurance to the customer that in the event we encounter significant financial or operational difficulties, the surety will arrange for the completion of our contractual obligations and for the payment of our vendors on the projects subject to the bonds. In cooperation with our lenders, we granted our sureties a first lien on assets such as receivables, costs and estimated earnings in excess of billings, and equipment specifically identifiable to projects for which bonds are outstanding, as collateral for potential obligations under bonds. As of December 31, 2020, the book value of these assets was approximately $167.8 million.

Covenants and Restrictions

The Facility contains financial covenants defining various financial measures and the levels of these measures with which we must comply. Covenant compliance is assessed as of each quarter end. Credit Facility Adjusted EBITDA is defined under the Facility for financial covenant purposes as net earnings for the four quarters ending as of any given quarterly covenant compliance measurement date, plus the corresponding amounts for (a) interest expense; (b) provision for income taxes; (c) depreciation and amortization; (d) stock compensation; (e) other non-cash charges; and (f) pre-acquisition results of acquired companies. The following is a reconciliation of Credit Facility Adjusted EBITDA to net income for 2020 (in thousands):


Net income	$	150,139
Provision for income taxes		41,401
Interest expense, net		8,282
Depreciation and amortization expense		60,629
Stock-based compensation		6,934
Pre-acquisition results of acquired companies, as defined under the Facility		18,511
Credit Facility Adjusted EBITDA	$	285,896

The Facility’s principal financial covenants include:

Total Leverage Ratio—The Facility requires that the ratio of our Consolidated Total Indebtedness to our Credit Facility Adjusted EBITDA not exceed 3.00 to 1.00 as of the end of each fiscal quarter. The leverage ratio as of December 31, 2020 was 0.8.

Fixed Charge Coverage Ratio—The Facility requires that the ratio of (a) Credit Facility Adjusted EBITDA, less non-financed capital expenditures, provision for income taxes, dividends and amounts used to repurchase stock when the Company’s Total Leverage Ratio exceeds 2.00 to 1.00 to (b) the sum of interest expense and scheduled principal payments of indebtedness be at least 1.50 to 1.00. Credit Facility Adjusted EBITDA, capital expenditures, provision for income taxes, dividends, stock repurchase payments, interest expense, and scheduled principal payments are defined under the Facility for purposes of this covenant, to be amounts for the four quarters ending as of any given quarterly covenant compliance measurement date. The fixed charge coverage ratio as of December 31, 2020 was 7.2.

Other Restrictions—The Facility permits acquisitions of up to $5.0 million per transaction, provided that the aggregate purchase price of such an acquisition and of acquisitions in the same fiscal year does not exceed $10.0 million. However, these limitations only apply when the Company’s Total Leverage Ratio is greater than 2.50 to 1.00.

While the Facility’s financial covenants do not specifically govern capacity under the Facility, if our debt level under the Facility at a quarter-end covenant compliance measurement date were to cause us to violate

the Facility’s leverage ratio covenant, our borrowing capacity under the Facility and the favorable terms that we currently have could be negatively impacted by the lenders.

We were in compliance with all of our financial covenants as of December 31, 2020.

Interest Rates and Fees

There are two interest rate options for borrowings under the Facility, the Base Rate Loan Option and the Eurodollar Rate Loan Option. Additional margins are then added to these two rates. Under the Base Rate Loan Option, the interest rate is determined based on the highest of the Federal Funds Rate plus 0.5%, the prime lending rate offered by Wells Fargo Bank, N.A. or the one-month Eurodollar Rate plus 1.00%. Under the Eurodollar Rate Loan Option, the interest rate is determined based on the one- to six-month Eurodollar Rate. The Eurodollar Rate corresponds very closely to rates described in various general business media sources as the London Interbank Offered Rate or “LIBOR.” Additional margins are then added to these rates. The additional margins are determined based on the ratio of our Consolidated Total Indebtedness as of a given quarter end to our “Credit Facility Adjusted EBITDA,” which shall mean Consolidated EBITDA as such term is defined in the credit agreement, for the twelve months ending as of that quarter end.

The interest rates under the Facility are floating rates determined by the broad financial markets, meaning they can and do move up and down from time to time. For illustrative purposes, the following are the respective market rates as of December 31, 2020 relating to interest options under the Facility:


Base Rate Loan Option:
Federal Funds Rate plus 0.50%		0.59%
Wells Fargo Bank, N.A. Prime Rate		3.25%
One-month LIBOR plus 1.00%		1.14%
Eurodollar Rate Loan Option:
One-month LIBOR		0.14%
Six-month LIBOR		0.26%

Certain of our vendors require letters of credit to ensure reimbursement for amounts they are disbursing on our behalf, such as to beneficiaries under our self-funded insurance programs. We have also occasionally used letters of credit to guarantee performance under our contracts and to ensure payment to our subcontractors and vendors under those contracts. Our lenders issue such letters of credit through the Facility. A letter of credit commits the lenders to pay specified amounts to the holder of the letter of credit if the holder demonstrates that we have failed to perform specified actions. If this were to occur, we would be required to reimburse the lenders for amounts they fund to honor the letter of credit holder’s claim. Absent a claim, there is no payment or reserving of funds by us in connection with a letter of credit. However, because a claim on a letter of credit would require immediate reimbursement by us to our lenders, letters of credit are treated as a use of facility capacity just the same as actual borrowings. We have never had a claim made against a letter of credit that resulted in payments by a lender or by us and believe such claim is unlikely in the foreseeable future.

Commitment fees are payable on the portion of the revolving loan capacity not in use for borrowings or letters of credit at any given time. Letter of credit fees and commitment fees are based on the ratio of Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA.


	Consolidated Total Indebtedness to
	Credit Facility Adjusted EBITDA
	Less than 1.00		1.00 to 1.75		1.75 to 2.50		2.50 or greater
Additional Per Annum Interest Margin Added Under:
Base Rate Loan Option	0.25	%	0.50	%	0.75	%	1.00	%
Eurodollar Rate Loan Option	1.25	%	1.50	%	1.75	%	2.00	%
Letter of credit fees	1.25	%	1.50	%	1.75	%	2.00	%
Commitment fees on any portion of the Revolving Loan capacity not in use for borrowings or letters of credit at any given time	0.20	%	0.25	%	0.30	%	0.35	%

The weighted average interest rate applicable to the borrowings under the revolving credit facility was approximately 1.4% as of December 31, 2020. The weighted average interest rate applicable to the term loan was approximately 1.4% as of December 31, 2020.

Notes to Former Owners

As part of the consideration used to acquire four companies, we have outstanding notes to the former owners. Together, these notes had an outstanding balance of $31.0 million as of December 31, 2020. In conjunction with the acquisition of T E C in the fourth quarter of 2020, we issued a promissory note to former owners with an outstanding balance of $7.0 million as of December 31, 2020 that bears interest, payable quarterly, at a stated interest rate of 2.5%. The principal is due in December 2023. In conjunction with the acquisition of TAS in the second quarter of 2020, we issued a promissory note to former owners with an outstanding balance of $8.0 million as of December 31, 2020 that bears interest, payable quarterly, at a stated interest rate of 3.5%. The principal is due in April 2022. In conjunction with the acquisition of the electrical contractor in North Carolina in the first quarter of 2020, we issued a promissory note to former owners with an outstanding balance of $6.0 million as of December 31, 2020 that bears interest, payable quarterly, at a stated interest rate of 3.0%. The principal is due in installments in February 2023 and February 2024. In conjunction with the Walker acquisition in the second quarter of 2019, we issued a promissory note to former owners with an outstanding balance of $10.0 million as of December 31, 2020 that bears interest, payable quarterly, at a stated interest rate of 4.0%. The remaining principal is due in April 2023.

Leases

12 Months Ended

Dec. 31, 2020

Leases

Leases

10. Leases

We lease certain facilities, vehicles and equipment under noncancelable operating leases. The most significant portion of these noncancelable operating leases are for the facilities occupied by our corporate office and our operating locations. Leases with an initial term of 12 months or less are not recorded on the Balance Sheet. We account for lease components separately from the non-lease components. We have certain leases with variable payments based on an index as well as some short-term leases on equipment and facilities. Variable lease expense and short-term lease expense were not material to our financial statements and aggregated to $7.7 million in 2020 and $8.4 million in 2019. Lease right-of-use assets and liabilities are recognized at commencement date based on the present value of lease payments over the lease term. As most of our leases do not provide an implicit rate, we generally use our incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. The weighted average discount rate as of December 31, 2020 and 2019 was 4.2% and 3.9%, respectively. We recognize lease expense, including escalating lease payments and lease incentives, on a straight-line basis over the lease term. Lease expense for the years ended December 31, 2020, 2019 and 2018 was $28.2 million, $24.8 million and $23.4 million, respectively.

The lease terms generally range from three to ten years. Some leases include one or more options to renew, which may be exercised to extend the lease term. We include the exercise of lease renewal options in the lease term when it is reasonably certain that we will exercise the option and such exercise is at our sole discretion. The weighted average remaining lease term was 7.5 years at December 31, 2020 and 8.1 years at December 31, 2019.

A majority of the Company’s real property leases are with individuals or entities with whom we have no other business relationship. However, in certain instances the Company enters into real property leases with current or former employees. Rent paid to related parties for the years ended December 31, 2020, 2019 and 2018 was approximately $4.2 million, $3.7 million and $4.8 million, respectively.

If we decide to cancel or terminate a lease before the end of its term, we would typically owe the lessor the remaining lease payments under the term of the lease. Our lease agreements do not contain any material residual value guarantees or material restrictive covenants. On rare occasions, we rent or sublease certain real estate assets that we no longer use to third parties.

The following table summarizes the lease assets and liabilities included in the consolidated Balance Sheet as follows (in thousands):


	December 31, 2020		December 31, 2019
Lease right-of-use assets	$	94,727	$	84,073
Lease liabilities:
Other current liabilities	$	16,586	$	14,016
Long-term lease liabilities		80,576		72,697
Total lease liabilities	$	97,162	$	86,713

The maturities of lease liabilities as of December 31, 2020 are as follows (in thousands):


Year ending December 31—
2021	$	20,254
2022		17,004
2023		14,727
2024		13,221
2025		12,108
Thereafter		36,645
Total Lease Payments		113,959
Less—Present Value Discount		(16,797)
Present Value of Lease Liabilities	$	97,162

Supplemental information related to leases was as follows (in thousands):


	Year Ended December 31,
	2020		2019
Cash paid for amounts included in the measurement of lease liabilities	$	20,443	$	16,895
Lease right-of-use assets obtained in exchange for lease liabilities	$	27,346	$	26,811

Income Taxes

12 Months Ended

Dec. 31, 2020

Income Taxes

Income Taxes

11. Income Taxes

Provision for Income Taxes

Our provision for income taxes relating to continuing operations consists of the following (in thousands):


	December 31,
	2020		2019		2018
Current tax provision—
Federal	$	36,556	$	33,281	$	22,728
State and Puerto Rico		12,798		8,388		8,589
Total current		49,354		41,669		31,317
Deferred tax provision (benefit)—
Federal		(5,483)		(3,750)		4,347
State and Puerto Rico		(2,470)		(501)		109
Total deferred		(7,953)		(4,251)		4,456
Provision for income taxes	$	41,401	$	37,418	$	35,773

The provision for income taxes for the years ended December 31, 2020, 2019 and 2018 resulted in effective tax rates on continuing operations of 21.6%, 24.7% and 24.1%, respectively. The reasons for the differences between these effective tax rates and the federal statutory rates are as follows (in thousands):


	December 31,
	2020			2019			2018
Federal statutory rate of—		21	%		21	%		21	%
Income taxes at the federal statutory rate	$	40,223		$	31,866		$	31,222
Increases (decreases) resulting from—
Net state income taxes		8,406			6,644			7,470
Valuation allowances		(254)			(279)			(2,852)
Net unrecognized tax benefits		18,557			7,338			(15)
Nondeductible expenses		2,470			2,180			1,926
R&D tax credit		(26,133)			(4,569)			(2,726)
179D deduction		(1,062)			(5,126)			—
Net operating loss carryforwards		—			—			2,225
Stock-based compensation deductions		(426)			(714)			(1,293)
Other		(380)			78			(184)
Provision for income taxes	$	41,401		$	37,418		$	35,773

Our provision for income taxes was reduced by $2.8 million in the first quarter of 2018 due to a reduction in unrecognized tax benefits from the filing of a federal income tax automatic accounting method change application.

In the third quarter of 2019, we filed an amended federal return for 2015 to claim the credit for increasing research activities (the “R&D tax credit”) and recorded a $4.6 million tax benefit that was fully offset by an addition to unrecognized tax benefits. We previously filed an amended federal return for 2014 to claim the R&D tax credit during 2018 and recorded a $2.7 million tax benefit that was also fully offset by an addition to unrecognized tax benefits. These $7.3 million of tax benefits were fully offset by additions to unrecognized tax benefits due to the uncertainty of the outcome from examinations opened by the Internal Revenue Service (the “IRS”). As a result, the R&D tax credit claimed had no impact on our effective tax rates.

During 2018, we dissolved our Puerto Rican subsidiary and thus wrote-off the remaining $2.2 million of net operating loss (“NOL”) carryforwards and related valuation allowance. The dissolution of our Puerto Rican subsidiary did not have an impact on our 2018 effective tax rate.

For the year ended December 31, 2019, our provision for income taxes was reduced by $2.2 million due to benefits from the filing, and expected filing, of amended returns to claim the energy efficient commercial buildings deduction (the “179D deduction”) allocated to us.

During the third quarter of 2020, the IRS completed its examination of our amended federal returns for 2014 and 2015 and issued a Revenue Agent Report (“RAR”) allowing the $8.9 million of refund claims in full. Subsequently, the Joint Committee on Taxation (the “JCT”) reviewed and approved the refund claims. As a result, our provision for income taxes was reduced by $8.3 million due to a reduction in unrecognized tax benefits of which $1.0 million related to the 179D deduction.

In early October 2020, we filed amended federal returns for 2016, 2017 and 2018 to claim the R&D tax credit and 179D deduction and recorded tax benefits of $6.1 million, $8.5 million and $11.9 million, respectively. The $26.5 million of tax benefits have been offset by additions to unrecognized tax benefits of $26.4 million due to the uncertainty of the outcome of future IRS examinations. The R&D tax credit and 179D deduction for 2016, 2017 and 2018, therefore, had no material impact on our effective tax rate for the year ended December 31, 2020. At this time, we cannot reasonably estimate the R&D tax credit for years after 2018 or 179D deduction for years after 2017.

Deferred Tax Assets (Liabilities)

Significant components of the deferred tax assets and deferred tax liabilities as reflected on the balance sheets are as follows (in thousands):


	Year Ended
	December 31,
	2020		2019
Deferred tax assets—
Accounts receivable and allowance for credit losses	$	2,186	$	1,660
Stock-based compensation		2,791		2,561
Accrued liabilities and expenses		39,761		25,569
Lease liabilities		22,768		20,873
Net operating loss carryforwards		12,127		2,750
Intangible assets		—		7,988
Other		627		525
Subtotal		80,260		61,926
Valuation allowances		(514)		(369)
Total deferred tax assets		79,746		61,557
Deferred tax liabilities—
Property and equipment		(13,877)		(11,286)
Lease right-of-use asset		(22,715)		(20,873)
Long-term contracts		(609)		(876)
Intangible assets		(242)		—
Goodwill		(11,615)		(6,020)
Other		(2,626)		(2,004)
Total deferred tax liabilities		(51,684)		(41,059)
Net deferred tax assets	$	28,062	$	20,498

The deferred tax assets and liabilities reflected above are included in the consolidated balance sheets as follows (in thousands):


	December 31,
	2020		2019
Deferred tax assets	$	29,401	$	21,923
Deferred tax liabilities	$	1,339	$	1,425

As of December 31, 2020, we had $9.4 million of deferred tax assets related to $44.9 million of federal NOL carryforwards as a result of the TAS acquisition. If not used, such carryforwards will begin to expire in 2031. We also had $2.7 million of deferred tax assets related to $46.2 million of state NOL carryforwards, including carryforwards acquired from TAS. The state NOL carryforwards will expire in varying amounts between the years 2021 and 2040. Valuation allowances of $0.5 million have been recorded against certain of the state NOL carryforwards. The $2.2 million of deferred tax assets for state NOL carryforwards, net of valuation allowances, reflects our conclusion that it is more-likely-than-not these assets will be realized based upon expected future earnings in certain of our subsidiaries.

Pursuant to Section 382 of the Code, utilization of our federal NOL carryforwards is subject to annual limitations due to the ownership change in TAS. In general, an ownership change, as defined by Section 382, results from transactions increasing the ownership of certain stockholders or public groups in the stock of a corporation by more than 50 percentage points over a three-year period.

We regularly update our assessment of the realizability of our deferred tax assets, in particular, those related to state NOL carryforwards. A return to profitability in our subsidiaries with valuation allowances would result in a release of a portion of the valuation allowances relating to realizable deferred tax assets. A sustained period of profitability could cause a change in our judgment of any remaining deferred tax assets. If that were to occur, then it is likely that we would reverse some or all of the remaining valuation allowances.

Liabilities for Uncertain Tax Positions

A reconciliation of the beginning and ending amount of unrecognized tax benefits, excluding accrued interest and penalties, is as follows (in thousands):


	Year Ended
	December 31,
	2020		2019		2018
Balance at beginning of year	$	10,199	$	2,966	$	8,929
Additions based on tax positions related to current year		—		—		—
Additions based on tax positions related to prior years		26,858		7,473		2,726
Reductions for tax positions related to prior years		—		(240)		(8,689)
Reductions for settlements with tax authorities		(8,301)		—		—
Balance at end of year	$	28,756	$	10,199	$	2,966

As of December 31, 2020, 2019 and 2018, we had $28.8 million, $10.2 million and $3.0 million, respectively, of unrecognized tax benefits, which if recognized in future periods, would impact our effective tax rates. We also had accrued zero, zero and $0.6 million for potential interest and penalties related to the unrecognized tax benefits as of December 31, 2020, 2019 and 2018, respectively. We recognize potential interest and penalties related to unrecognized tax benefits in our provision for income taxes.

We are subject to taxation in the United States and various state jurisdictions. During 2019, the IRS commenced an examination of our amended federal returns for 2014 and 2015. The IRS completed its examination and issued an RAR allowing our refund claims in full, which was reviewed and approved by the JCT during the third quarter of 2020. As a result, our unrecognized tax benefits were reduced by $8.3 million. In late January 2021, we received notification from the IRS that our federal returns for 2017 and 2018 were selected for examination. The completion of this IRS examination could impact our future results of operations and financial condition.

State income tax returns are generally subject to examination for a period of three to four years after filing the returns. However, the state impact of any federal audit adjustments and/or amendments remains subject to examination by various states for up to one year after formal notification to the states. We generally remain open to examination by various state tax authorities for the 2016 tax year forward. As of December 31, 2020, we did not have any state audits underway that would have a material impact on our financial position or results of operations.

We believe it is reasonably possible that a reduction of up to $28.8 million in unrecognized tax benefits could occur within the next twelve months. Any reduction in our unrecognized tax benefits, due to the future recognition of those tax benefits, would affect our effective tax rates.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References + Details

Employee Benefit Plans

12 Months Ended

Dec. 31, 2020

Employee Benefit Plans

Employee Benefit Plans

12. Employee Benefit Plans

We and certain of our subsidiaries sponsor various retirement plans for most full-time and some part-time employees. These plans primarily consist of defined contribution plans. The defined contribution plans generally provide for contributions up to 2.5% of covered employees’ salaries or wages. These contributions totaled $16.3 million in 2020, $14.2 million in 2019 and $10.8 million in 2018. Of these amounts, approximately $0.5 million and $0.3 million were payable to the plans at December 31, 2020 and 2019, respectively.

Certain of our subsidiaries also participate or have participated in various multi-employer pension plans for the benefit of employees who are union members. As of December 31, 2020 and 2019, we had 6 and 7, respectively, who were union members. There were no contributions made to multi-employer pension plans in 2020, 2019 or 2018. The data available from administrators of other multi-employer pension plans is not sufficient to determine the accumulated benefit obligations, nor the net assets attributable to the multi-employer plans in which our employees participate or previously participated.

Certain individuals at one of our operating units are entitled to receive fixed annual payments that reach a maximum amount, as specified in the related agreements, for a 15 year period following retirement or, in some cases, the attainment of 65 years of age. We recognize the unfunded status of the plan as a non-current liability in our Consolidated Balance Sheet. Benefits vest 50% after ten years of service, 75% after fifteen years of service and are fully vested after

20 years of service. We had an unfunded benefit liability of $4.0 million and $4.1 million recorded as of December 31, 2020 and 2019, respectively.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2020

Commitments and Contingencies

Commitments and Contingencies

13. Commitments and Contingencies

Claims and Lawsuits

We are subject to certain legal and regulatory claims, including lawsuits arising in the normal course of business. We maintain various insurance coverages to minimize financial risk associated with these claims. We have estimated and provided accruals for probable losses and related legal fees associated with certain litigation in the accompanying consolidated financial statements. While we cannot predict the outcome of these proceedings, in management’s opinion and based on reports of counsel, any liability arising from these matters individually and in the aggregate will not have a material effect on our operating results, cash flows or financial condition, after giving effect to provisions already recorded.

We are in a dispute with a customer regarding the outcome of a completed project and also regarding the obligation to perform subcontract work under two executed letters of intent for subsequent projects that we believe are not enforceable. The customer is claiming approximately $15 million in damages related to performance of the original project as well as excess costs to perform the work that was subject to the letters of intent. We are claiming approximately $9 million composed of unpaid amounts under the completed contract as well as costs and inefficiencies that we suffered. We have a lien on the project, and this matter is currently scheduled for arbitration in the second quarter of 2021 with a likely decision in the following months. As of December 31, 2020, we recorded an accrual for this matter based on our analysis of likely outcomes related to this dispute; however, it is possible that the ultimate outcome and associated costs will deviate from our estimates and that, in the event of an unexpectedly adverse outcome, we may experience additional costs and expenses in future periods.

Surety

Many customers, particularly in connection with new construction, require us to post performance and payment bonds issued by a financial institution known as a surety. If we fail to perform under the terms of a contract or to pay subcontractors and vendors who provided goods or services under a contract, the customer may demand that the surety make payments or provide services under the bond. We must reimburse the surety for any expenses or outlays it incurs. To date, we are not aware of any losses to our sureties in connection with bonds the sureties have posted on our behalf, and do not expect such losses to be incurred in the foreseeable future.

Current market conditions for surety markets and bonding capacity are adequate with acceptable terms and conditions. Historically, approximately 15% to 25% of our business has required bonds. While we currently have strong surety relationships to support our bonding needs, future market conditions or changes in the sureties’ assessment of our operating and financial risk could cause the sureties to decline to issue bonds for our work. If that were to occur, the alternatives include doing more business that does not require bonds, posting other forms of collateral for project performance such as letters of credit or cash, and seeking bonding capacity from other sureties. We would likely also encounter concerns from customers, suppliers and other market participants as to our creditworthiness. While we believe our general operating and financial characteristics would enable us to ultimately respond effectively to an interruption in the availability of bonding capacity, such an interruption would likely cause our revenue and profits to decline in the near term.

Self-Insurance

We are substantially self-insured for workers’ compensation, employer’s liability, auto liability, general liability and employee group health claims, in view of the relatively high per-incident deductibles we absorb under our insurance arrangements for these risks. Losses are estimated and accrued based upon known facts, historical trends and industry averages. Estimated losses in excess of our deductible, which have not already been paid, are included in our accrual with a corresponding receivable from our insurance carrier. Loss estimates associated with the larger and longer-developing risks, such as workers’ compensation, auto liability and general liability, are reviewed by a third-party actuary quarterly.

Our self-insurance arrangements as of December 31, 2020 were as follows:

Workers’ Compensation—The per-incident deductible for workers’ compensation is $250,000. Losses above $250,000 are determined by statutory rules on a state-by-state basis and are fully covered by excess workers’ compensation insurance.

Employer’s Liability—For employer’s liability, the per-incident deductible is $250,000 and then we have several layers of excess loss insurance policies that cover losses up to $132.5 million in aggregate across this risk area (as well as general liability and auto liability noted below).

General Liability—For general liability, the per-incident deductible is $250,000. We are fully insured for the next $10.0 million of each loss, and then have several layers of excess loss insurance policies that cover losses up to $132.5 million in aggregate across this risk area (as well as employer’s liability noted above and auto liability noted below).

Auto Liability—For auto liability, the per-incident deductible is $250,000. We are fully insured for the next $10.0 million of each loss, and then have several layers of excess loss insurance policies that cover losses up to $132.5 million in aggregate across this risk area (as well as employer’s liability and general liability noted above).

Employee Medical—We have three medical plans. The deductible for employee group health claims is $350,000 per person, per policy (calendar) year for each plan. Insurance then covers any responsibility for medical claims in excess of the deductible amount.

Our $132.5 million of aggregate excess loss coverage above applicable per-incident deductibles represents one policy limit that applies to all lines of risk; we do not have a separate $132.5 million of excess loss coverage for each of general liability, employer’s liability and auto liability.

Stockholders' Equity

12 Months Ended

Dec. 31, 2020

Stockholders' Equity

Stockholders' Equity

14. Stockholders’ Equity

2012 Equity Incentive Plan

In May 2012, our stockholders approved our 2012 Equity Incentive Plan (the “2012 Plan”), which provides for the granting of incentive or non-qualified stock options, stock appreciation rights, restricted or deferred stock, dividend equivalents or other incentive awards to directors, employees, or consultants. The number of shares authorized and reserved for issuance under the 2012 Plan is 5.1 million shares. As of December 31, 2020, there were 2.9 million shares available for issuance under this plan; however, following adoption of the 2017 Plan (described below), no additional shares will be issued under the 2012 Plan. The 2012 Plan will expire in May 2022.

2017 Omnibus Incentive Plan

In May 2017, our stockholders approved our 2017 Omnibus Incentive Plan (the “2017 Plan”), which provides for the granting of incentive or non-qualified stock options, stock appreciation rights, restricted or deferred stock, dividend equivalents or other incentive awards to directors, employees, or consultants. The number of shares authorized and reserved for issuance under the 2017 Plan is 2.9 million shares. As of December 31, 2020, there were 2.0 million shares available for issuance under this plan. The 2017 Plan will expire in May 2027. Additionally, we have outstanding stock options, stock awards and stock units that were issued under other plans, and no further grants may be made under those plans.

Share Repurchase Program

On March 29, 2007, our Board of Directors approved a stock repurchase program to acquire up to 1.0 million shares of our outstanding common stock. Subsequently, the Board has from time to time increased the number of shares that may be acquired under the program and approved extensions of the program. On December 8, 2020, the Board approved an extension to the program by increasing the shares authorized for repurchase by 0.7 million shares. Since the inception of the repurchase program, the Board has approved 10.3 million shares to be repurchased. As of December 31,

2020, we have repurchased a cumulative total of 9.3 million shares at an average price of $19.63 per share under the repurchase program.

The share repurchases will be made from time to time at our discretion in the open market or privately negotiated transactions as permitted by securities laws and other legal requirements, and subject to market conditions and other factors. The Board may modify, suspend, extend or terminate the program at any time. During the twelve months ended December 31, 2020, we repurchased 0.7 million shares for approximately $30.1 million at an average price of $43.99 per share.

Earnings Per Share

Basic earnings per share (“EPS”) is computed by dividing net income by the weighted average number of shares of common stock outstanding during the year. Diluted EPS is computed considering the dilutive effect of stock options, restricted stock, restricted stock units and performance stock units. The vesting of unvested contingently issuable performance stock units is based on the achievement of certain earnings per share targets and total shareholder return. These shares are considered contingently issuable shares for purposes of calculating diluted earnings per share. These shares are not included in the diluted earnings per share denominator until the performance criteria are met, if it is assumed that the end of the reporting period was the end of the contingency period.

Unvested restricted stock, restricted stock units and performance stock units are included in diluted earnings per share, weighted outstanding until the shares and units vest. Upon vesting, the vested restricted stock, restricted stock units and performance stock units are included in basic earnings per share weighted outstanding from the vesting date.

There were less than 0.1 million anti-dilutive stock options excluded from the calculation of diluted EPS for the years ended December 31, 2020, 2019 and 2018, respectively.

The following table reconciles the number of shares outstanding with the number of shares used in computing basic and diluted earnings per share for each of the periods presented (in thousands):



	Year Ended December 31,
	2020	2019	2018
Common shares outstanding, end of period	36,188	36,658	36,894
Effect of using weighted average common shares outstanding	354	196	308
Shares used in computing earnings per share—basic	36,542	36,854	37,202
Effect of shares issuable under stock option plans based on the treasury stock method	123	204	283
Effect of restricted and contingently issuable shares	73	73	107
Shares used in computing earnings per share—diluted	36,738	37,131	37,592

Stock-Based Compensation

12 Months Ended

Dec. 31, 2020

Stock-Based Compensation

Stock-Based Compensation

15. Stock-Based Compensation

Grants of stock options, restricted stock and restricted stock units, and performance share units have been, under the 2012 Plan and under the 2017 Plan, determined and administered by the compensation committee of the Board of Directors. In 2019, the Board of Directors approved a change to the structure of long-term incentive grants to remove stock options, commencing with the March 2019 equity grant. Total stock-based compensation expense was $6.9 million, $5.9 million and $7.2 million for the years ended December 31, 2020, 2019 and 2018, respectively. Stock-based compensation expense is recognized using the straight-line method over the vesting period and generally vests over a three-year vesting period. Certain awards provide for accelerated vesting when the sum of an employee's age and years of service is at least 75. We recognize forfeitures as they occur. Total income tax benefit recognized for stock-based compensation arrangements was $1.5 million, $1.3 million and $1.5 million for each of the years ended December 31, 2020, 2019 and 2018.

We generally issue treasury shares for stock options and restricted stock, unless treasury shares are not available. Upon the vesting of restricted shares, we have allowed the holder to elect to surrender an amount of shares to meet their statutory tax withholding requirements. These shares are accounted for as treasury stock based upon the value of the stock on the date of vesting.

Stock Options

The following table summarizes activity under our stock option plans (shares in thousands):


	Year Ended
	December 31,
	2020
		Weighted-
		Average
Stock Options	Shares	Exercise Price
Outstanding at beginning of year	382	$	27.06
Granted	—	$	—
Exercised	(114)	$	18.85
Forfeited	—	$	—
Expired	—	$	—
Outstanding at end of year	268	$	30.53
Options exercisable at end of year	241

The total intrinsic value of options exercised during the years ended December 31, 2020, 2019 and 2018 was $3.2 million, $3.5 million and $6.7 million, respectively. Stock options exercisable as of December 31, 2020 have a weighted-average remaining contractual term of 5.2 years and an aggregate intrinsic value of $5.7 million. As of December 31, 2020, we have 0.3 million options that are vested or expected to vest; these options have a weighted average exercise price of $30.53 per share, have a weighted-average remaining contractual term of 5.4 years and an aggregate intrinsic value of $5.9 million.

The following table summarizes information about stock options outstanding at December 31, 2020 (shares in thousands):


	Options Outstanding				Options Exercisable
		Weighted-
		Average
	Number	Remaining	Weighted-		Number	Weighted-
	Outstanding at	Contractual	Average		Exercisable at	Average
Range of Exercise Prices	12/31/2020	Life (in years)	Exercise Price		12/31/2020	Exercise Price
$11.21 - $15.00	14	2.2	$	13.76	14	$	13.76
$15.01 - $35.00	130	4.4	$	23.54	130	$	23.54
$35.01 - $42.50	124	6.8	$	39.78	97	$	39.02
$11.21 - $42.50	268	5.4	$	30.53	241	$	29.18

The fair value of each option award is estimated, based on several assumptions, on the date of grant using the Black-Scholes option valuation model. We did not grant any options in 2019 or 2020. The fair values and the assumptions used for the 2018 grant are shown in the table below:



	2018
Weighted-average fair value per share of options granted	$	13.06
Fair value assumptions:
Expected dividend yield		0.79%
Expected stock price volatility		31.7%
Risk-free interest rate		2.66%
Expected term		5.3 years

Stock options are accounted for as equity instruments. As of December 31, 2020, the unrecognized compensation cost related to stock options was less than $0.1 million, which is expected to be recognized over a weighted-average period of 0.3 years. The total fair value of options vested during the year ended December 31, 2020 was $0.7 million.

The following table summarizes information about nonvested stock option awards as of December 31, 2020 and changes for the year ended December 31, 2020 (shares in thousands):


		Weighted-Average
		Grant Date
Stock Options	Shares	Fair Value
Nonvested at December 31, 2019	81	$	12.53
Granted	—	$	—
Vested	(54)	$	12.26
Forfeited	—	$	—
Nonvested at December 31, 2020	27	$	13.06

Restricted Stock and Restricted Stock Units

The following table summarizes activity under our restricted stock plans (shares in thousands):


	Year Ended
	December 31,
	2020
		Weighted
		Average Grant
Restricted Stock and Restricted Stock Units	Shares	Date Fair Value
Unvested at beginning of year	91	$	47.58
Granted	118	$	39.03
Vested	(85)	$	39.13
Forfeited	(4)	$	45.21
Unvested at end of year	120	$	45.21

Approximately $1.1 million of compensation expense related to restricted stock and restricted stock units will be recognized over a weighted-average period of 1.8 years. The total fair value of shares vested during the year ended December 31, 2020 was $3.3 million. The weighted-average fair value per share of restricted stock shares and units awarded during 2020, 2019 and 2018 was $39.03, $51.02 and $44.02, respectively. The aggregate intrinsic value of restricted stock vested during the years ended December 31, 2020, 2019 and 2018 was $2.9 million, $3.5 million and $3.3 million, respectively.

Performance Stock Units

Under the 2012 Plan, we granted dollar-denominated performance vesting restricted stock units (“PSUs”), which cliff vest at the end of a three-year performance period. The PSUs are subject to two performance measures; 50% of the PSUs are based on the annual performance of our stock price relative to a group of our peers (total shareholder return) and 50% of the PSUs are measured based on meeting or exceeding a pre-determined annual earnings per share target as set by our Board of Directors (EPS). Depending on the Company’s performance in relation to the established performance measures, the awards may vest at zero to a maximum of 2.0 times the dollar-denominated award granted at target. Upon achievement of the necessary performance metrics, the award will be determined in dollars and may be settled in cash or stock based on the market price of the Company’s common stock at the end of the performance period, at our discretion.

Compensation expense for dollar-denominated performance units will ultimately be equal to the final dollar value awarded to the grantee upon vesting, settled either in cash or stock. However, throughout the performance period we must record and accrue expense based on an estimate of that future payout. For units determined by EPS performance, the awards are evaluated quarterly against established targets in order to estimate the liability throughout the vesting period. For units determined by total shareholder return performance, a Monte Carlo simulation model was used to estimate accruals throughout the vesting period. The model simulates our total shareholder return and compares it against our peer group over the three-year performance period to produce a predicted distribution of relative share performance. This is applied to the reward criteria to give an expected value of the total shareholder return element. The calculated fair market value as of December 31, 2020 was $6.2 million. Of this amount, $2.2 million relates to the PSUs granted in 2018 whose performance period ended December 31, 2020. These awards will be settled within the upcoming

year either in cash or stock. The expense related to performance stock units for the years ended December 31, 2020, 2019 and 2018 was $2.7 million, $1.9 million and $2.9 million, respectively. At the December 31, 2020 calculated fair market value, approximately $0.7 million of compensation expense related to performance stock units will be recognized over a weighted-average period of 1.4 years.

Segment Information

12 Months Ended

Dec. 31, 2020

Segment Information

Segment Information

16. Segment Information

We have two reportable segments: (a) our mechanical segment, which includes HVAC, plumbing, piping, and controls, as well as off-site construction, monitoring and fire protection; and (b) our electrical segment, which includes installation and servicing of electrical systems. We consider these two lines of business to be separate segments because they require different skill sets, and the business models for providing services have some differences, as a mechanical system requires ongoing maintenance and monitoring and an electrical system generally does not. However, the business model for installation of new systems or retrofitting existing systems is very similar between the two segments.

Our activities are within the mechanical services industry and the electrical services industry, which represent our two reportable segments. We aggregate our operating segments into two reportable segments, as the operating segments meet all of the aggregation criteria. Substantially all of our revenue is generated, and all of our assets are located, in the United States, our country of domicile. The following table presents information about our reportable segments (in thousands):


	Mechanical Services		Electrical Services		Corporate		Consolidated
Total Assets at December 31, 2020	$	1,215,985	$	449,588	$	91,782	$	1,757,355
Total Assets at December 31, 2019	$	1,056,609	$	372,254	$	76,149	$	1,505,012

	Year Ended December 31, 2020
	Mechanical Services		Electrical Services		Corporate		Consolidated
Revenue	$	2,413,016	$	443,643	$	—	$	2,856,659
Gross Profit	$	509,740	$	37,243	$	—	$	546,983
Capital Expenditures	$	22,550	$	955	$	626	$	24,131

	Year Ended December 31, 2019
	Mechanical Services		Electrical Services		Corporate		Consolidated
Revenue	$	2,251,560	$	363,717	$	—	$	2,615,277
Gross Profit	$	465,144	$	36,799	$	—	$	501,943
Capital Expenditures	$	27,933	$	1,504	$	2,313	$	31,750

	Year Ended December 31, 2018
	Mechanical Services		Electrical Services		Corporate		Consolidated
Revenue	$	2,176,223	$	6,656	$	—	$	2,182,879
Gross Profit	$	444,960	$	1,319	$	—	$	446,279
Capital Expenditures	$	25,945	$	57	$	1,266	$	27,268

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 31
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8924-108599

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8981-108599

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 21
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8721-108599

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 40
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9031-108599

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 26
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8844-108599

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9038-108599

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9054-108599

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8657-108599

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 21
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8721-108599

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-URI http://asc.fasb.org/topic&trid=2134510

+ Details

Selected Quarterly Financial Data

12 Months Ended

Dec. 31, 2020

Selected Quarterly Financial Data

Selected Quarterly Financial Data

17. Selected Quarterly Financial Data

Quarterly financial information for the years ended December 31, 2020 and 2019 is summarized as follows (in thousands, except per share data):


	2020
	Q1		Q2		Q3		Q4
Revenue	$	700,131	$	743,468	$	714,099	$	698,961
Gross profit		117,093		145,695		147,196		136,999
Net income		17,716		39,495		50,088		42,840
INCOME PER SHARE:
Basic	$	0.48	$	1.08	$	1.37	$	1.18
Diluted	$	0.48	$	1.08	$	1.36	$	1.17


	2019
	Q1		Q2		Q3		Q4
Revenue	$	538,473	$	650,302	$	706,918	$	719,584
Gross profit (1)		106,665		120,016		142,702		132,560
Net income		19,866		24,173		36,233		34,052
INCOME PER SHARE:
Basic	$	0.54	$	0.65	$	0.98	$	0.93
Diluted	$	0.53	$	0.65	$	0.98	$	0.92

(1)

In the fourth quarter of 2019, we recorded a $4.8 million gain due to insurance proceeds we received in the fourth quarter related to the ransomware incident that occurred in April 2019.

The sums of the individual quarterly earnings per share amounts do not necessarily agree with year-to-date earnings per share as each quarter’s computation is based on the weighted average number of shares outstanding during the quarter, the weighted average stock price during the quarter and the dilutive effects of options and contingently issuable restricted stock in each quarter.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2020

Summary of Significant Accounting Policies

Principles of Consolidation

Use of Estimates

Cash Flow Information

We consider all highly liquid investments purchased with an original maturity of three months or less to be cash equivalents.

Cash paid (in thousands) for:


	Year Ended December 31,
	2020		2019		2018
Interest	$	7,684	$	8,817	$	3,743
Income taxes, net of refunds	$	51,286	$	45,288	$	33,401

Recent Accounting Pronouncements

Revenue Recognition

Accounts Receivable and Allowance for Credit Losses

Activity in our allowance for credit losses consisted of the following (in thousands):


	Year Ended December 31,
	2020
	Service		Construction		Other		Total
Balance at beginning of year	$	3,192	$	3,400	$	315	$	6,907
Impact of new accounting standard		310		331		54		695
Bad debt expense (benefit)		2,566		2,697		(10)		5,253
Deductions for uncollectible receivables written off, net of recoveries		(1,431)		(735)		—		(2,166)
Credit allowance of acquired companies on the acquisition date		—		335		—		335
Reclass to other current liabilities		—		—		(315)		(315)
Balance at December 31, 2020	$	4,637	$	6,028	$	44	$	10,709


	Year Ended December 31,
	2019
Balance at beginning of year	$	5,898
Bad debt expense (benefit)		2,978
Deductions for uncollectible receivables written off, net of recoveries		(3,924)
Credit allowance of acquired companies on the acquisition date		1,955
Balance at December 31, 2019	$	6,907

Inventories

Property and Equipment

Recoverability of Goodwill and Identifiable Intangible Assets

Long-Lived Assets

Acquisitions

We recognize assets acquired and liabilities assumed in business combinations, including contingent assets and liabilities, based on fair value estimates as of the date of acquisition.

Self-Insurance Liabilities

Warranty Costs

Income Taxes

Concentrations of Credit Risk

Financial Instruments

Insurance Recovery

Leases

The following table summarizes the lease assets and liabilities included in the consolidated Balance Sheet as follows (in thousands):


	December 31, 2020		December 31, 2019
Lease right-of-use assets	$	94,727	$	84,073
Lease liabilities:
Other current liabilities	$	16,586	$	14,016
Long-term lease liabilities		80,576		72,697
Total lease liabilities	$	97,162	$	86,713

The maturities of lease liabilities as of December 31, 2020 are as follows (in thousands):


Year ending December 31—
2021	$	20,254
2022		17,004
2023		14,727
2024		13,221
2025		12,108
Thereafter		36,645
Total Lease Payments		113,959
Less—Present Value Discount		(16,797)
Present Value of Lease Liabilities	$	97,162

Supplemental information related to leases was as follows (in thousands):


	Year Ended December 31,
	2020		2019
Cash paid for amounts included in the measurement of lease liabilities	$	20,443	$	16,895
Lease right-of-use assets obtained in exchange for lease liabilities	$	27,346	$	26,811

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2020

Summary of Significant Accounting Policies

Schedule of cash paid

Cash paid (in thousands) for:


	Year Ended December 31,
	2020		2019		2018
Interest	$	7,684	$	8,817	$	3,743
Income taxes, net of refunds	$	51,286	$	45,288	$	33,401

Schedule of activity in allowance for credit losses

Activity in our allowance for credit losses consisted of the following (in thousands):


	Year Ended December 31,
	2020
	Service		Construction		Other		Total
Balance at beginning of year	$	3,192	$	3,400	$	315	$	6,907
Impact of new accounting standard		310		331		54		695
Bad debt expense (benefit)		2,566		2,697		(10)		5,253
Deductions for uncollectible receivables written off, net of recoveries		(1,431)		(735)		—		(2,166)
Credit allowance of acquired companies on the acquisition date		—		335		—		335
Reclass to other current liabilities		—		—		(315)		(315)
Balance at December 31, 2020	$	4,637	$	6,028	$	44	$	10,709


	Year Ended December 31,
	2019
Balance at beginning of year	$	5,898
Bad debt expense (benefit)		2,978
Deductions for uncollectible receivables written off, net of recoveries		(3,924)
Credit allowance of acquired companies on the acquisition date		1,955
Balance at December 31, 2019	$	6,907

Revenue from Contracts with Customers (Tables)

12 Months Ended

Dec. 31, 2020

Revenue from Contract with Customers

Schedule of contracts in progress

Contracts in progress are as follows (in thousands):


	December 31,
	2020		2019
Costs incurred on contracts in progress	$	3,103,580	$	2,518,581
Estimated earnings, net of losses		548,435		405,891
Less—Billings to date		(3,813,171)		(3,033,112)
Less—Unbilled accounts receivable		(45,596)		(55,542)
Less—Unbilled accounts receivable credit allowance		(784)		—
	$	(207,536)	$	(164,182)

Costs and estimated earnings in excess of billings	$	18,622	$	2,736
Plus—Costs and estimated earnings in excess of billings credit allowance		79		—
Billings in excess of costs and estimated earnings		(226,237)		(166,918)
	$	(207,536)	$	(164,182)

Schedule of disaggregation of revenue


	Year Ended December 31,
Revenue by Service Provided	2020				2019				2018
Mechanical Services	$	2,413,016	84.5	%	$	2,251,560	86.1	%	$	2,176,223	99.7	%
Electrical Services		443,643	15.5	%		363,717	13.9	%		6,656	0.3	%
Total	$	2,856,659	100.0	%	$	2,615,277	100.0	%	$	2,182,879	100.0	%

	Year Ended December 31,
Revenue by Type of Customer	2020				2019				2018
Industrial	$	1,112,075	38.9	%	$	886,668	33.9	%	$	596,557	27.3	%
Education		487,922	17.1	%		412,318	15.8	%		391,937	18.0	%
Office Buildings		319,426	11.2	%		348,640	13.3	%		288,090	13.2	%
Healthcare		371,105	13.0	%		358,155	13.7	%		319,958	14.7	%
Government		163,717	5.7	%		162,507	6.2	%		143,958	6.6	%
Retail, Restaurants and Entertainment		239,541	8.4	%		248,083	9.5	%		225,348	10.3	%
Multi-Family and Residential		86,799	3.0	%		104,693	4.0	%		136,075	6.2	%
Other		76,074	2.7	%		94,213	3.6	%		80,956	3.7	%
Total	$	2,856,659	100.0	%	$	2,615,277	100.0	%	$	2,182,879	100.0	%

	Year Ended December 31,
Revenue by Activity Type	2020				2019				2018
New Construction	$	1,333,739	46.7	%	$	1,201,122	45.9	%	$	829,978	38.0	%
Existing Building Construction		910,807	31.9	%		793,159	30.3	%		796,946	36.5	%
Service Projects		241,402	8.4	%		231,228	8.9	%		206,506	9.5	%
Service Calls, Maintenance and Monitoring		370,711	13.0	%		389,768	14.9	%		349,449	16.0	%
Total	$	2,856,659	100.0	%	$	2,615,277	100.0	%	$	2,182,879	100.0	%

Schedule of contract assets and liabilities


	Year Ended December 31,					Year Ended December 31,
	2020				2019
	Contract		Contract		Contract		Contract
	Assets		Liabilities		Assets		Liabilities
Balance at beginning of period	$	2,736	$	166,918	$	10,213	$	130,986
Change due to acquisitions / disposals		9,509		39,885		6,573		31,556
Change related to credit allowance		(79)		—		—		—
Other changes in the period		6,456		19,434		(14,050)		4,376
Balance at end of period	$	18,622	$	226,237	$	2,736	$	166,918

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2020

Fair Value Measurements

Summary of fair values and levels within the fair value hierarchy in which the fair value measurements fall for assets and liabilities measured on a recurring basis


	Fair Value Measurements at December 31, 2020
	Level 1		Level 2		Level 3		Total
Cash and cash equivalents	$	54,896	$	—	$	—	$	54,896
Life insurance—cash surrender value	$	—	$	5,420	$	—	$	5,420
Contingent earn-out obligations	$	—	$	—	$	25,979	$	25,979
Interest rate swap liability	$	—	$	42	$	—	$	42

	Fair Value Measurements at December 31, 2019
	Level 1		Level 2		Level 3		Total
Cash and cash equivalents	$	50,788	$	—	$	—	$	50,788
Life insurance—cash surrender value	$	—	$	3,905	$	—	$	3,905
Contingent earn-out obligations	$	—	$	—	$	28,497	$	28,497

Schedule of reconciliation of the fair value of contingent earn-out obligations that use significant unobservable inputs (Level 3)

The table below presents a reconciliation of the fair value of our contingent earn-out obligations that use significant unobservable inputs (Level 3) (in thousands):


	December 31,
	2020		2019
Balance at beginning of year	$	28,497	$	7,375
Issuances		16,715		19,500
Settlements		(10,114)		(1,369)
Adjustments to fair value		(9,119)		2,991
Balance at end of year	$	25,979	$	28,497

Acquisitions (Tables)

12 Months Ended

Dec. 31, 2020

TAS Energy

Business Acquisition [Line Items]

Schedule of acquisition date fair value of consideration transferred and the acquisition date fair value of the identifiable assets acquired and liabilities assumed, including an amount for goodwill


Consideration transferred:
Cash paid at closing	$	105,950
Working capital adjustment		40,455
Notes issued to former owners		14,000
Estimated fair value of contingent earn-out payments		9,100
	$	169,505
Recognized amounts of identifiable assets acquired and liabilities assumed:
Cash and cash equivalents	$	47,460
Billed and unbilled accounts receivable		18,702
Other current assets		15,634
Other long-term assets		1,556
Property and equipment		7,709
Goodwill		72,788
Identifiable intangible assets		53,400
Lease right-of-use asset		19,736
Accounts payable		(16,453)
Billings in excess of costs and estimated earnings		(24,196)
Current lease liabilities		(2,337)
Accrued expenses and other current liabilities		(4,109)
Long-term lease liabilities		(17,398)
Other long-term liabilities		(2,987)
	$	169,505

Schedule of acquired intangible assets

The acquired intangible assets include the following (dollars in thousands):


	Valuation Method	Estimated Useful Life		Estimated Fair Value
Backlog	Excess earnings	1 year	$	5,200
Trade Name	Relief-from-royalty	25 years		8,200
Customer Relationships	Excess earnings	10 years		40,000
Total			$	53,400

T E C Industrial Construction and Maintenance

Business Acquisition [Line Items]

Schedule of acquisition date fair value of consideration transferred and the acquisition date fair value of the identifiable assets acquired and liabilities assumed, including an amount for goodwill


Consideration transferred:
Cash paid at closing	$	73,000
Working capital adjustment		2,006
Notes issued to former owners		7,000
Estimated fair value of contingent earn-out payments		7,560
	$	89,566
Recognized amounts of identifiable assets acquired and liabilities assumed:
Cash and cash equivalents	$	4
Billed and unbilled accounts receivable		13,660
Costs in excess of billings		2,040
Other current assets		108
Other long-term assets		53
Property and equipment		912
Goodwill		44,431
Identifiable intangible assets		37,200
Lease right-of-use asset		1,234
Accounts payable		(4,123)
Billings in excess of costs and estimated earnings		(2,838)
Current lease liabilities		(175)
Accrued expenses and other current liabilities		(1,881)
Long-term lease liabilities		(1,059)
	$	89,566

Schedule of acquired intangible assets

The acquired intangible assets include the following (dollars in thousands):


	Valuation	Estimated	Estimated
	Method	Useful Life	Fair Value
Backlog	Excess earnings	2 years	$	7,200
Trade Name	Relief-from-royalty	20 years		5,800
Customer Relationships	Excess earnings	9 years		24,200
Total			$	37,200

Goodwill and Identifiable Intangible Assets, Net (Tables)

12 Months Ended

Dec. 31, 2020

Goodwill and Identifiable Intangible Assets, Net

Schedule of changes in the carrying amount of goodwill

The changes in the carrying amount of goodwill are as follows (in thousands):


	Mechanical Services		Electrical Services
	Segment		Segment		Total
Balance at December 31, 2018	$	235,182	$	—	$	235,182
Acquisitions and purchase price adjustments (See Note 5)		579		96,686		97,265
Impact of segment reorganization		(1,101)		1,101		—
Balance at December 31, 2019		234,660		97,787		332,447
Acquisitions and purchase price adjustments (See Note 5)		72,788		59,157		131,945
Balance at December 31, 2020	$	307,448	$	156,944	$	464,392

Schedule of components of identifiable intangible assets

Identifiable intangible assets consist of the following (dollars in thousands):


	Weighted-Average	December 31, 2020				December 31, 2019
	Remaining Useful Lives	Gross Book		Accumulated		Gross Book		Accumulated
	in Years	Value		Amortization		Value		Amortization
Customer Relationships	8.0	$	255,692	$	(103,919)	$	183,061	$	(80,813)
Backlog	2.0		19,800		(12,600)		7,400		(6,388)
Trade Names	20.5		91,495		(18,661)		71,995		(15,281)
Total	11.7	$	366,987	$	(135,180)	$	262,456	$	(102,482)

Schedule of future amortization expense of identifiable intangible assets

As of December 31, 2020, future amortization expense of identifiable intangible assets was as follows (in thousands):


Year ended December 31—
2021	$	32,344
2022		27,412
2023		23,514
2024		22,164
2025		19,977
Thereafter		106,396
Total	$	231,807

Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2020

Property and Equipment

Schedule of components of property and equipment

Property and equipment consist of the following (dollars in thousands):


	Estimated
	Useful Lives	December 31,
	in Years	2020		2019
Land	—	$	7,167	$	6,206
Transportation equipment	1 - 7		113,802		106,972
Machinery and equipment	1 - 20		43,386		35,575
Computer and telephone equipment	1 - 10		23,215		20,744
Buildings and leasehold improvements	1 - 40		69,683		62,301
Furniture and fixtures	1 - 17		5,861		5,244
Construction in progress	—		1,294		2,123
			264,408		239,165
Less—Accumulated depreciation			(147,202)		(129,369)
Property and equipment, net		$	117,206	$	109,796

Detail of Other Current Liabilities (Tables)

12 Months Ended

Dec. 31, 2020

Detail of Other Current Liabilities

Schedule of other current liabilities

Other current liabilities consist of the following (in thousands):


	December 31,
	2020		2019
Accrued warranty costs	$	8,914	$	7,452
Current lease liability		16,586		14,016
Accrued job losses		2,151		2,226
Accrued sales and use tax		3,731		2,938
Deferred revenue		4,559		5,506
Liabilities due to former owners		10,280		11,219
Other current liabilities		45,271		38,273
	$	91,492	$	81,630

Debt Obligations (Tables)

12 Months Ended

Dec. 31, 2020

Debt Obligations

Schedule of components of debt obligations

Debt obligations consist of the following (in thousands):


	December 31,
	2020		2019
Revolving credit facility	$	70,000	$	28,000
Term loan		135,000		150,000
Notes to former owners		31,000		48,483
Total principal amount		236,000		226,483
Less—unamortized debt issuance costs		(267)		(348)
Total debt, net of unamortized debt issuance costs		235,733		226,135
Less—current portion		—		(20,817)
Total long-term portion of debt, net	$	235,733	$	205,318

Schedule of future principal payments of long-term debt

At December 31, 2020, future principal payments of debt are as follows (in thousands):


Year ended December 31—
2021	$	—
2022		23,000
2023		34,000
2024		26,500
2025		152,500
Thereafter		—
	$	236,000

Schedule of interest expense

Interest expense included the following primary elements (in thousands):


	Year Ended December 31,
	2020		2019		2018
Interest expense on notes to former owners	$	1,354	$	1,531	$	642
Interest expense on borrowings and unused commitment fees		5,319		6,887		2,211
Interest expense on interest rate swaps		338		—		—
Letter of credit fees		830		512		474
Amortization of debt financing costs		544		387		383
Total	$	8,385	$	9,317	$	3,710

Schedule of reconciliation of Credit Facility Adjusted EBITDA to net income


Net income	$	150,139
Provision for income taxes		41,401
Interest expense, net		8,282
Depreciation and amortization expense		60,629
Stock-based compensation		6,934
Pre-acquisition results of acquired companies, as defined under the Facility		18,511
Credit Facility Adjusted EBITDA	$	285,896

Schedule of market rates relating to interest options under the Facility


Base Rate Loan Option:
Federal Funds Rate plus 0.50%		0.59%
Wells Fargo Bank, N.A. Prime Rate		3.25%
One-month LIBOR plus 1.00%		1.14%
Eurodollar Rate Loan Option:
One-month LIBOR		0.14%
Six-month LIBOR		0.26%

Summary of additional margins


	Consolidated Total Indebtedness to
	Credit Facility Adjusted EBITDA
	Less than 1.00		1.00 to 1.75		1.75 to 2.50		2.50 or greater
Additional Per Annum Interest Margin Added Under:
Base Rate Loan Option	0.25	%	0.50	%	0.75	%	1.00	%
Eurodollar Rate Loan Option	1.25	%	1.50	%	1.75	%	2.00	%
Letter of credit fees	1.25	%	1.50	%	1.75	%	2.00	%
Commitment fees on any portion of the Revolving Loan capacity not in use for borrowings or letters of credit at any given time	0.20	%	0.25	%	0.30	%	0.35	%

Leases (Tables)

12 Months Ended

Dec. 31, 2020

Leases

Schedule of lease assets and liabilities

The following table summarizes the lease assets and liabilities included in the consolidated Balance Sheet as follows (in thousands):


	December 31, 2020		December 31, 2019
Lease right-of-use assets	$	94,727	$	84,073
Lease liabilities:
Other current liabilities	$	16,586	$	14,016
Long-term lease liabilities		80,576		72,697
Total lease liabilities	$	97,162	$	86,713

Schedule of maturities of lease liabilities

The maturities of lease liabilities as of December 31, 2020 are as follows (in thousands):


Year ending December 31—
2021	$	20,254
2022		17,004
2023		14,727
2024		13,221
2025		12,108
Thereafter		36,645
Total Lease Payments		113,959
Less—Present Value Discount		(16,797)
Present Value of Lease Liabilities	$	97,162

Schedule of supplemental information related to leases

Supplemental information related to leases was as follows (in thousands):


	Year Ended December 31,
	2020		2019
Cash paid for amounts included in the measurement of lease liabilities	$	20,443	$	16,895
Lease right-of-use assets obtained in exchange for lease liabilities	$	27,346	$	26,811

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

Income Taxes

Schedule of provision for income taxes relating to continuing operations

Our provision for income taxes relating to continuing operations consists of the following (in thousands):


	December 31,
	2020		2019		2018
Current tax provision—
Federal	$	36,556	$	33,281	$	22,728
State and Puerto Rico		12,798		8,388		8,589
Total current		49,354		41,669		31,317
Deferred tax provision (benefit)—
Federal		(5,483)		(3,750)		4,347
State and Puerto Rico		(2,470)		(501)		109
Total deferred		(7,953)		(4,251)		4,456
Provision for income taxes	$	41,401	$	37,418	$	35,773

Schedule of difference in income taxes provided for and the amounts determined by applying the federal statutory tax rate to income before income taxes results


	December 31,
	2020			2019			2018
Federal statutory rate of—		21	%		21	%		21	%
Income taxes at the federal statutory rate	$	40,223		$	31,866		$	31,222
Increases (decreases) resulting from—
Net state income taxes		8,406			6,644			7,470
Valuation allowances		(254)			(279)			(2,852)
Net unrecognized tax benefits		18,557			7,338			(15)
Nondeductible expenses		2,470			2,180			1,926
R&D tax credit		(26,133)			(4,569)			(2,726)
179D deduction		(1,062)			(5,126)			—
Net operating loss carryforwards		—			—			2,225
Stock-based compensation deductions		(426)			(714)			(1,293)
Other		(380)			78			(184)
Provision for income taxes	$	41,401		$	37,418		$	35,773

Schedule of significant components of the net deferred tax assets and net deferred tax liabilities as reflected on the balance sheet

Significant components of the deferred tax assets and deferred tax liabilities as reflected on the balance sheets are as follows (in thousands):


	Year Ended
	December 31,
	2020		2019
Deferred tax assets—
Accounts receivable and allowance for credit losses	$	2,186	$	1,660
Stock-based compensation		2,791		2,561
Accrued liabilities and expenses		39,761		25,569
Lease liabilities		22,768		20,873
Net operating loss carryforwards		12,127		2,750
Intangible assets		—		7,988
Other		627		525
Subtotal		80,260		61,926
Valuation allowances		(514)		(369)
Total deferred tax assets		79,746		61,557
Deferred tax liabilities—
Property and equipment		(13,877)		(11,286)
Lease right-of-use asset		(22,715)		(20,873)
Long-term contracts		(609)		(876)
Intangible assets		(242)		—
Goodwill		(11,615)		(6,020)
Other		(2,626)		(2,004)
Total deferred tax liabilities		(51,684)		(41,059)
Net deferred tax assets	$	28,062	$	20,498

Schedule of deferred income tax assets and liabilities included in the consolidated balance sheets

The deferred tax assets and liabilities reflected above are included in the consolidated balance sheets as follows (in thousands):


	December 31,
	2020		2019
Deferred tax assets	$	29,401	$	21,923
Deferred tax liabilities	$	1,339	$	1,425

Schedule of reconciliation of the beginning and ending amount of unrecognized tax benefits, excluding accrued interest and penalties

A reconciliation of the beginning and ending amount of unrecognized tax benefits, excluding accrued interest and penalties, is as follows (in thousands):


	Year Ended
	December 31,
	2020		2019		2018
Balance at beginning of year	$	10,199	$	2,966	$	8,929
Additions based on tax positions related to current year		—		—		—
Additions based on tax positions related to prior years		26,858		7,473		2,726
Reductions for tax positions related to prior years		—		(240)		(8,689)
Reductions for settlements with tax authorities		(8,301)		—		—
Balance at end of year	$	28,756	$	10,199	$	2,966

Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2020

Stockholders' Equity

Reconciliation of number of shares outstanding with the number of shares used in computing basic and diluted earnings per share

The following table reconciles the number of shares outstanding with the number of shares used in computing basic and diluted earnings per share for each of the periods presented (in thousands):



	Year Ended December 31,
	2020	2019	2018
Common shares outstanding, end of period	36,188	36,658	36,894
Effect of using weighted average common shares outstanding	354	196	308
Shares used in computing earnings per share—basic	36,542	36,854	37,202
Effect of shares issuable under stock option plans based on the treasury stock method	123	204	283
Effect of restricted and contingently issuable shares	73	73	107
Shares used in computing earnings per share—diluted	36,738	37,131	37,592

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2020

Stock-Based Compensation

Summary of activity under the entity's stock option plans

The following table summarizes activity under our stock option plans (shares in thousands):


	Year Ended
	December 31,
	2020
		Weighted-
		Average
Stock Options	Shares	Exercise Price
Outstanding at beginning of year	382	$	27.06
Granted	—	$	—
Exercised	(114)	$	18.85
Forfeited	—	$	—
Expired	—	$	—
Outstanding at end of year	268	$	30.53
Options exercisable at end of year	241

Summary information about stock options outstanding

The following table summarizes information about stock options outstanding at December 31, 2020 (shares in thousands):


	Options Outstanding				Options Exercisable
		Weighted-
		Average
	Number	Remaining	Weighted-		Number	Weighted-
	Outstanding at	Contractual	Average		Exercisable at	Average
Range of Exercise Prices	12/31/2020	Life (in years)	Exercise Price		12/31/2020	Exercise Price
$11.21 - $15.00	14	2.2	$	13.76	14	$	13.76
$15.01 - $35.00	130	4.4	$	23.54	130	$	23.54
$35.01 - $42.50	124	6.8	$	39.78	97	$	39.02
$11.21 - $42.50	268	5.4	$	30.53	241	$	29.18

Schedule of fair values and the assumptions used for the grants



	2018
Weighted-average fair value per share of options granted	$	13.06
Fair value assumptions:
Expected dividend yield		0.79%
Expected stock price volatility		31.7%
Risk-free interest rate		2.66%
Expected term		5.3 years

Summary of information about nonvested stock option awards and changes

The following table summarizes information about nonvested stock option awards as of December 31, 2020 and changes for the year ended December 31, 2020 (shares in thousands):


		Weighted-Average
		Grant Date
Stock Options	Shares	Fair Value
Nonvested at December 31, 2019	81	$	12.53
Granted	—	$	—
Vested	(54)	$	12.26
Forfeited	—	$	—
Nonvested at December 31, 2020	27	$	13.06

Summary of activity under the entity's restricted stock plans

The following table summarizes activity under our restricted stock plans (shares in thousands):


	Year Ended
	December 31,
	2020
		Weighted
		Average Grant
Restricted Stock and Restricted Stock Units	Shares	Date Fair Value
Unvested at beginning of year	91	$	47.58
Granted	118	$	39.03
Vested	(85)	$	39.13
Forfeited	(4)	$	45.21
Unvested at end of year	120	$	45.21

Segment Information (Tables)

12 Months Ended

Dec. 31, 2020

Segment Information

Summary of information about reportable segments


	Mechanical Services		Electrical Services		Corporate		Consolidated
Total Assets at December 31, 2020	$	1,215,985	$	449,588	$	91,782	$	1,757,355
Total Assets at December 31, 2019	$	1,056,609	$	372,254	$	76,149	$	1,505,012

	Year Ended December 31, 2020
	Mechanical Services		Electrical Services		Corporate		Consolidated
Revenue	$	2,413,016	$	443,643	$	—	$	2,856,659
Gross Profit	$	509,740	$	37,243	$	—	$	546,983
Capital Expenditures	$	22,550	$	955	$	626	$	24,131

	Year Ended December 31, 2019
	Mechanical Services		Electrical Services		Corporate		Consolidated
Revenue	$	2,251,560	$	363,717	$	—	$	2,615,277
Gross Profit	$	465,144	$	36,799	$	—	$	501,943
Capital Expenditures	$	27,933	$	1,504	$	2,313	$	31,750

	Year Ended December 31, 2018
	Mechanical Services		Electrical Services		Corporate		Consolidated
Revenue	$	2,176,223	$	6,656	$	—	$	2,182,879
Gross Profit	$	444,960	$	1,319	$	—	$	446,279
Capital Expenditures	$	25,945	$	57	$	1,266	$	27,268

Selected Quarterly Financial Data (Tables)

12 Months Ended

Dec. 31, 2020

Selected Quarterly Financial Data

Schedule of quarterly financial information

Quarterly financial information for the years ended December 31, 2020 and 2019 is summarized as follows (in thousands, except per share data):


	2020
	Q1		Q2		Q3		Q4
Revenue	$	700,131	$	743,468	$	714,099	$	698,961
Gross profit		117,093		145,695		147,196		136,999
Net income		17,716		39,495		50,088		42,840
INCOME PER SHARE:
Basic	$	0.48	$	1.08	$	1.37	$	1.18
Diluted	$	0.48	$	1.08	$	1.36	$	1.17


	2019
	Q1		Q2		Q3		Q4
Revenue	$	538,473	$	650,302	$	706,918	$	719,584
Gross profit (1)		106,665		120,016		142,702		132,560
Net income		19,866		24,173		36,233		34,052
INCOME PER SHARE:
Basic	$	0.54	$	0.65	$	0.98	$	0.93
Diluted	$	0.53	$	0.65	$	0.98	$	0.92

(1)

In the fourth quarter of 2019, we recorded a $4.8 million gain due to insurance proceeds we received in the fourth quarter related to the ransomware incident that occurred in April 2019.

Business and Organization (Details)	12 Months Ended
Business and Organization (Details)	Dec. 31, 2020
Installation of systems in newly constructed facilities
Business and Organization
Percentage of revenue attributable to services	46.70%
Maintenance, repair and replacement services
Business and Organization
Percentage of revenue attributable to services	53.30%

Summary of Significant Accounting Policies - Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash paid for:
Interest	$ 7,684	$ 8,817	$ 3,743
Income taxes	$ 51,286	$ 45,288	$ 33,401

Summary of Significant Accounting Policies - Recent Accounting Pronouncements (Details) - USD ($) $ in Thousands	Jan. 01, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle
Impact to Retained Earnings		$ 696,429	$ 585,304	$ 498,047	$ 417,945
Lease right-of-use assets		94,727	84,073
Operating lease liability		97,162	$ 86,713
Cumulative Effect, Period of Adoption, Adjustment [Member]
New Accounting Pronouncements or Change in Accounting Principle
Impact to Retained Earnings		$ (515)
Cumulative Effect, Period of Adoption, Adjustment [Member] \| ASU 2016-13
New Accounting Pronouncements or Change in Accounting Principle
Impact to Retained Earnings	$ 500
Adjustments \| ASU 2016-13
New Accounting Pronouncements or Change in Accounting Principle
Increase in Allowance for Credit Losses	700
Increase to Deferred Tax Assets	$ 200

- Definition

Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

+ References + Details

Summary of Significant Accounting Policies - Allowance for Credit Losses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of year	$ 6,907	$ 5,898
Impact of new accounting standard	695
Bad debt expense (benefit)	5,253	2,978	$ 3,562
Deductions for uncollectible receivables written off, net of recoveries	(2,166)	(3,924)
Credit allowance of acquired companies on the acquisition date	335	1,955
Reclass to other current liabilities	(315)
Balance at end of year	10,709	6,907	$ 5,898
Service
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of year	3,192
Impact of new accounting standard	310
Bad debt expense (benefit)	2,566
Deductions for uncollectible receivables written off, net of recoveries	(1,431)
Balance at end of year	4,637	3,192
Construction
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of year	3,400
Impact of new accounting standard	331
Bad debt expense (benefit)	2,697
Deductions for uncollectible receivables written off, net of recoveries	(735)
Credit allowance of acquired companies on the acquisition date	335
Balance at end of year	6,028	3,400
Other.
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of year	315
Impact of new accounting standard	54
Bad debt expense (benefit)	(10)
Reclass to other current liabilities	(315)
Balance at end of year	$ 44	$ 315

Summary of Significant Accounting Policies - Risk (Details)	12 Months Ended
	Dec. 31, 2020
Warranty Costs
Labor warranty period after servicing of existing MEP system	30 days
Revenue \| Customer concentration \| Minimum
Warranty Costs
Single customer, percentage of revenue	5.00%

Summary of Significant Accounting Policies - Insurance Recovery (Details) $ in Millions	3 Months Ended
	Dec. 31, 2019 USD ($)
Summary of Significant Accounting Policies
Gain due to insurance proceeds received	$ 4.8
Gain recorded as reduction in SG&A	1.6
Gain recorded as reduction in cost of services expense	$ 3.2

Revenue from Contracts with Customers - Revenue Recognition (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Contracts in progress
Costs incurred on contracts in progress	$ 3,103,580	$ 2,518,581
Estimated earnings, net of losses	548,435	405,891
Less-Billings to date	(3,813,171)	(3,033,112)
Less-Unbilled accounts receivable	(45,596)	(55,542)
Less-Unbilled accounts receivable credit allowance	(784)	0
Contracts in progress	(207,536)	(164,182)
Costs and estimated earnings in excess of billings	18,622	2,736	$ 10,213
Plus-Costs and estimated earnings in excess of billings credit allowance	79	0
Billings in excess of costs and estimated earnings	$ (226,237)	(166,918)	$ (130,986)
Period during which progress billings or contract price can be withheld until completion of work	6 months
Retention receivable	$ 124,100	111,700
Retention payable	$ 22,200	$ 15,800
Revenue, Performance Obligation, Description of Payment Terms	We typically invoice our customers with payment terms of net due in 30 days
Receivable payment terms (in days)	30 days
Minimum
Contracts in progress
Receivable payment terms (in days)	45 days
Payments received term (in days)	30 days
Maximum
Contracts in progress
Receivable payment terms (in days)	60 days
Payments received term (in days)	90 days

Revenue from Contracts with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue
Revenue	$ 2,856,659	$ 2,615,277
Percentage of revenue from contract with customer (as a percent)	100.00%	100.00%
Industrial
Disaggregation of Revenue
Revenue	$ 1,112,075	$ 886,668
Percentage of revenue from contract with customer (as a percent)	38.90%	33.90%
Education
Disaggregation of Revenue
Revenue	$ 487,922	$ 412,318
Percentage of revenue from contract with customer (as a percent)	17.10%	15.80%
Office Buildings
Disaggregation of Revenue
Revenue	$ 319,426	$ 348,640
Percentage of revenue from contract with customer (as a percent)	11.20%	13.30%
Healthcare
Disaggregation of Revenue
Revenue	$ 371,105	$ 358,155
Percentage of revenue from contract with customer (as a percent)	13.00%	13.70%
Government
Disaggregation of Revenue
Revenue	$ 163,717	$ 162,507
Percentage of revenue from contract with customer (as a percent)	5.70%	6.20%
Retail, Restaurants and Entertainment
Disaggregation of Revenue
Revenue	$ 239,541	$ 248,083
Percentage of revenue from contract with customer (as a percent)	8.40%	9.50%
Multi-Family and Residential
Disaggregation of Revenue
Revenue	$ 86,799	$ 104,693
Percentage of revenue from contract with customer (as a percent)	3.00%	4.00%
Other
Disaggregation of Revenue
Revenue	$ 76,074	$ 94,213
Percentage of revenue from contract with customer (as a percent)	2.70%	3.60%
New Construction
Disaggregation of Revenue
Revenue	$ 1,333,739	$ 1,201,122
Percentage of revenue from contract with customer (as a percent)	46.70%	45.90%
Existing Building Construction
Disaggregation of Revenue
Revenue	$ 910,807	$ 793,159
Percentage of revenue from contract with customer (as a percent)	31.90%	30.30%
Service Projects
Disaggregation of Revenue
Revenue	$ 241,402	$ 231,228
Percentage of revenue from contract with customer (as a percent)	8.40%	8.90%
Service Calls, Maintenance and Monitoring
Disaggregation of Revenue
Revenue	$ 370,711	$ 389,768
Percentage of revenue from contract with customer (as a percent)	13.00%	14.90%
Mechanical Services
Disaggregation of Revenue
Revenue	$ 2,413,016	$ 2,251,560
Percentage of revenue from contract with customer (as a percent)	84.50%	86.10%
Electrical Services
Disaggregation of Revenue
Revenue	$ 443,643	$ 363,717
Percentage of revenue from contract with customer (as a percent)	15.50%	13.90%
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue
Revenue			$ 2,182,879
Percentage of revenue from contract with customer (as a percent)			100.00%
Calculated under Revenue Guidance in Effect before Topic 606 [Member] \| Industrial
Disaggregation of Revenue
Revenue			$ 596,557
Percentage of revenue from contract with customer (as a percent)			27.30%
Calculated under Revenue Guidance in Effect before Topic 606 [Member] \| Education
Disaggregation of Revenue
Revenue			$ 391,937
Percentage of revenue from contract with customer (as a percent)			18.00%
Calculated under Revenue Guidance in Effect before Topic 606 [Member] \| Office Buildings
Disaggregation of Revenue
Revenue			$ 288,090
Percentage of revenue from contract with customer (as a percent)			13.20%
Calculated under Revenue Guidance in Effect before Topic 606 [Member] \| Healthcare
Disaggregation of Revenue
Revenue			$ 319,958
Percentage of revenue from contract with customer (as a percent)			14.70%
Calculated under Revenue Guidance in Effect before Topic 606 [Member] \| Government
Disaggregation of Revenue
Revenue			$ 143,958
Percentage of revenue from contract with customer (as a percent)			6.60%
Calculated under Revenue Guidance in Effect before Topic 606 [Member] \| Retail, Restaurants and Entertainment
Disaggregation of Revenue
Revenue			$ 225,348
Percentage of revenue from contract with customer (as a percent)			10.30%
Calculated under Revenue Guidance in Effect before Topic 606 [Member] \| Multi-Family and Residential
Disaggregation of Revenue
Revenue			$ 136,075
Percentage of revenue from contract with customer (as a percent)			6.20%
Calculated under Revenue Guidance in Effect before Topic 606 [Member] \| Other
Disaggregation of Revenue
Revenue			$ 80,956
Percentage of revenue from contract with customer (as a percent)			3.70%
Calculated under Revenue Guidance in Effect before Topic 606 [Member] \| New Construction
Disaggregation of Revenue
Revenue			$ 829,978
Percentage of revenue from contract with customer (as a percent)			38.00%
Calculated under Revenue Guidance in Effect before Topic 606 [Member] \| Existing Building Construction
Disaggregation of Revenue
Revenue			$ 796,946
Percentage of revenue from contract with customer (as a percent)			36.50%
Calculated under Revenue Guidance in Effect before Topic 606 [Member] \| Service Projects
Disaggregation of Revenue
Revenue			$ 206,506
Percentage of revenue from contract with customer (as a percent)			9.50%
Calculated under Revenue Guidance in Effect before Topic 606 [Member] \| Service Calls, Maintenance and Monitoring
Disaggregation of Revenue
Revenue			$ 349,449
Percentage of revenue from contract with customer (as a percent)			16.00%
Calculated under Revenue Guidance in Effect before Topic 606 [Member] \| Mechanical Services
Disaggregation of Revenue
Revenue			$ 2,176,223
Percentage of revenue from contract with customer (as a percent)			99.70%
Calculated under Revenue Guidance in Effect before Topic 606 [Member] \| Electrical Services
Disaggregation of Revenue
Revenue			$ 6,656
Percentage of revenue from contract with customer (as a percent)			0.30%

Revenue from Contracts with Customers - Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Contract Assets
Balance at beginning of period	$ 2,736	$ 10,213
Change due to acquisitions / disposals	9,509	6,573
Change related to credit allowance	(79)
Other changes in the period	6,456	(14,050)
Balance at end of period	18,622	2,736
Contract Liabilities
Balance at beginning of period	166,918	130,986
Change due to acquisitions / disposals	39,885	31,556
Other changes in the period	19,434	4,376
Balance at end of period	226,237	166,918
Revenue related to our contract liabilities	$ 165,800
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Contract Liabilities
Revenue related to our contract liabilities		$ 126,700

Revenue from Contracts with Customers - Remaining Performance Obligations (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($)
Remaining Performance Obligations
The term of the renewable service maintenance agreements (in years)	1 year
Practical Expedient	true
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Remaining Performance Obligations
Remaining performance obligations	$ 1,510
Expected timing of performance obligations	12 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01 \| Minimum
Remaining Performance Obligations
Expected percentage of remaining performance obligations	80.00%
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01 \| Maximum
Remaining Performance Obligations
Expected percentage of remaining performance obligations	85.00%

Fair Value Measurements (Details) $ in Thousands	12 Months Ended
Fair Value Measurements (Details) $ in Thousands	Dec. 31, 2020 USD ($) item	Dec. 31, 2019 USD ($)	Nov. 30, 2021 USD ($)
Fair Value Measurements
Number of employees covered under life insurance policies \| item	86
Combined face value of life insurance policies	$ 61,700
Cash surrender value	$ 5,400	$ 3,900
Minimum
Fair Value Measurements
Weighted average cost of capital	9.50%
Maximum
Fair Value Measurements
Weighted average cost of capital	17.00%
Contingent earn-out obligations
Reconciliation of the fair value of contingent earn-out obligations that use significant unobservable inputs (Level 3)
Balance at beginning of year	$ 28,497	7,375
Issuances	16,715	19,500
Settlements	(10,114)	(1,369)
Adjustments to fair value	9,119	(2,991)
Balance at end of period	25,979	28,497
Recurring basis \| Total
Fair Value Measurements
Cash and cash equivalents	54,896	50,788
Life insurance-cash surrender value	5,420	3,905
Contingent earn-out obligations	25,979	28,497
Recurring basis \| Quoted Market Prices In Active Markets for Identical Assets (Level 1)
Fair Value Measurements
Cash and cash equivalents	54,896	50,788
Recurring basis \| Fair Value Measurements at Reporting Date Using Significant Other Observable Inputs (Level 2)
Fair Value Measurements
Life insurance-cash surrender value	5,420	3,905
Recurring basis \| Significant Unobservable Inputs (Level 3)
Fair Value Measurements
Contingent earn-out obligations	25,979	$ 28,497
Non recurring basis \| Significant Unobservable Inputs (Level 3)
Reconciliation of the fair value of contingent earn-out obligations that use significant unobservable inputs (Level 3)
Impairment charges	0
Interest Rate Swap
Fair Value Measurements
Net loss on derivative	300
Interest Rate Swap \| Not Designated as Hedging Instrument, Economic Hedge [Member]
Fair Value Measurements
Notional amount	130,000		$ 80,000
Interest Rate Swap \| Recurring basis \| Total \| Not Designated as Hedging Instrument, Economic Hedge [Member]
Fair Value Measurements
Interest rate swap liability	42
Interest Rate Swap \| Recurring basis \| Fair Value Measurements at Reporting Date Using Significant Other Observable Inputs (Level 2) \| Not Designated as Hedging Instrument, Economic Hedge [Member]
Fair Value Measurements
Interest rate swap liability	$ 42

Acquisitions (Details) - USD ($) $ in Thousands		1 Months Ended	3 Months Ended	12 Months Ended
Acquisitions (Details) - USD ($) $ in Thousands	Apr. 01, 2020	Dec. 31, 2020	Jun. 30, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Consideration transferred:
Total consideration transferred				$ 41,600	$ 2,600
Recognized amounts of identifiable assets acquired and liabilities assumed:
Goodwill		$ 464,392		464,392	$ 332,447	$ 235,182
TAS Energy
Consideration transferred:
Cash paid at closing	$ 105,950
Working capital adjustment	40,455
Notes issued to former owners	14,000
Estimated fair value of contingent earn-out payments	9,100
Total consideration transferred	169,505
Recognized amounts of identifiable assets acquired and liabilities assumed:
Cash and cash equivalents	47,460
Billed and unbilled accounts receivable	18,702
Other current assets	15,634
Other long-term assets	1,556
Property and equipment	7,709
Goodwill	72,788
Identifiable intangible assets	53,400
Lease right-of-use asset	19,736
Accounts payable	(16,453)
Billings in excess of costs and estimated earnings	(24,196)
Current lease liabilities	(2,337)
Accrued expenses and other current liabilities	(4,109)
Long-term lease liabilities	(17,398)
Other long-term liabilities	(2,987)
Total assets acquired and liabilities assumed	$ 169,505
T E C Industrial Construction and Maintenance
Consideration transferred:
Cash paid at closing		73,000
Working capital adjustment		2,006
Notes issued to former owners		7,000
Estimated fair value of contingent earn-out payments		7,560
Total consideration transferred		89,566
Recognized amounts of identifiable assets acquired and liabilities assumed:
Cash and cash equivalents		4		4
Billed and unbilled accounts receivable		13,660		13,660
Costs in excess of billings		2,040		2,040
Other current assets		108		108
Other long-term assets		53		53
Property and equipment		912		912
Goodwill		44,431		44,431
Identifiable intangible assets		37,200		37,200
Lease right-of-use asset		1,234		1,234
Accounts payable		(4,123)		(4,123)
Billings in excess of costs and estimated earnings		(2,838)		(2,838)
Current lease liabilities		(175)		(175)
Accrued expenses and other current liabilities		(1,881)		(1,881)
Long-term lease liabilities		(1,059)		(1,059)
Total assets acquired and liabilities assumed		$ 89,566		$ 89,566
Walker
Consideration transferred:
Cash paid at closing			$ 178,000
Working capital adjustment			7,800
Notes issued to former owners			25,000
Total consideration transferred			235,400
Recognized amounts of identifiable assets acquired and liabilities assumed:
Total assets acquired and liabilities assumed			$ 187,000

Acquisitions - Acquired Intangible Assets (Details) - USD ($) $ in Thousands		1 Months Ended
	Apr. 01, 2020	Dec. 31, 2020
TAS Energy
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Fair Value	$ 53,400
TAS Energy \| Backlog
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life	1 year
Estimated Fair Value	$ 5,200
TAS Energy \| Trade Name
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life	25 years
Estimated Fair Value	$ 8,200
TAS Energy \| Customer Relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life	10 years
Estimated Fair Value	$ 40,000
T E C Industrial Construction and Maintenance
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Fair Value		$ 37,200
T E C Industrial Construction and Maintenance \| Backlog
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life		2 years
Estimated Fair Value		$ 7,200
T E C Industrial Construction and Maintenance \| Trade Name
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life		20 years
Estimated Fair Value		$ 5,800
T E C Industrial Construction and Maintenance \| Customer Relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life		9 years
Estimated Fair Value		$ 24,200

Acquisitions - Contingent Earn-out Obligation (Details) - USD ($) $ in Thousands		1 Months Ended	3 Months Ended								9 Months Ended	12 Months Ended
	Apr. 01, 2020	Dec. 31, 2020	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Revenues			$ 698,961	$ 714,099	$ 743,468	$ 700,131	$ 719,584	$ 706,918	$ 650,302	$ 538,473		$ 2,856,659	$ 2,615,277	$ 2,182,879
Federal
Business Acquisition [Line Items]
Net operating loss carryforwards	$ 53,200	$ 44,900	44,900								$ 44,900	44,900
State
Business Acquisition [Line Items]
Net operating loss carryforwards	$ 6,500	$ 46,200	46,200								46,200	46,200
TAS Energy
Business Acquisition [Line Items]
Revenues											106,400
Contingent earn-out period	27 months
Contingent earn-out estimated milestone payment, minimum	$ 1,000
Contingent earn-out estimated milestone payment, maximum	$ 8,000
Cash flow discount rate	17.70%
TAS Energy \| Minimum
Business Acquisition [Line Items]
Cash flow discount rate	15.00%
TAS Energy \| Maximum
Business Acquisition [Line Items]
Cash flow discount rate	23.50%
T E C Industrial Construction and Maintenance
Business Acquisition [Line Items]
Contingent earn-out period		3 years
Contingent earn-out estimated milestone payment, minimum		$ 1,000	1,000								1,000	1,000
Contingent earn-out estimated milestone payment, maximum		$ 5,000	$ 5,000								$ 5,000	$ 5,000
Cash flow discount rate		12.90%
T E C Industrial Construction and Maintenance \| Minimum
Business Acquisition [Line Items]
Cash flow discount rate		14.00%
T E C Industrial Construction and Maintenance \| Maximum
Business Acquisition [Line Items]
Cash flow discount rate		15.00%

Acquisitions - Other Acquisitions (Details) $ in Millions	3 Months Ended	12 Months Ended
Acquisitions - Other Acquisitions (Details) $ in Millions	Jun. 30, 2019 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($) item
Acquisitions
Number of acquisitions \| item			2
Total purchase price		$ 41.6	$ 2.6
Walker
Acquisitions
Total purchase price	$ 235.4
Amount allocated to goodwill and intangible assets for acquisitions	187.0
Purchase price paid in cash	178.0
Promissory note payable	25.0
Advance to former owners	20.5
Contingent earn-out obligation	19.5
Tax equalization payment	0.2
Working capital adjustment	$ 7.8

Goodwill and Identifiable Intangible Assets, Net - Changes in Carrying Amount of Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Changes in the carrying amount of goodwill
Balance at beginning of year	$ 332,447	$ 235,182
Acquisitions and purchase price adjustments (See Note 5)	131,945	97,265
Balance at end of period	464,392	332,447
Mechanical Services Segment
Changes in the carrying amount of goodwill
Balance at beginning of year	234,660	235,182
Acquisitions and purchase price adjustments (See Note 5)	72,788	579
Impact of segment reorganization		(1,101)
Balance at end of period	307,448	234,660
Accumulated impairment charges	116,600	116,600
Electrical Services
Changes in the carrying amount of goodwill
Balance at beginning of year	97,787
Acquisitions and purchase price adjustments (See Note 5)	59,157	96,686
Impact of segment reorganization		1,101
Balance at end of period	$ 156,944	$ 97,787

Goodwill and Identifiable Intangible Assets, Net - Identifiable Intangible Assets, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Identifiable Intangible Assets, Net
Estimated Useful Lives in Years	11 years 8 months 12 days
Gross Book Value	$ 366,987	$ 262,456
Accumulated Amortization	(135,180)	(102,482)
Amortization of identifiable intangible assets	32,698	27,082	$ 20,089
Future amortization expense of identifiable intangible assets
2021	32,344
2022	27,412
2023	23,514
2024	22,164
2025	19,977
Thereafter	106,396
Total	$ 231,807
Customer Relationships
Identifiable Intangible Assets, Net
Estimated Useful Lives in Years	8 years
Gross Book Value	$ 255,692	183,061
Accumulated Amortization	$ (103,919)	(80,813)
Customer Relationships \| Minimum
Identifiable Intangible Assets, Net
Estimated Useful Lives in Years	8 years
Backlog
Identifiable Intangible Assets, Net
Estimated Useful Lives in Years	2 years
Gross Book Value	$ 19,800	7,400
Accumulated Amortization	$ (12,600)	(6,388)
Backlog \| Minimum
Identifiable Intangible Assets, Net
Estimated Useful Lives in Years	2 years
Trade Name
Identifiable Intangible Assets, Net
Estimated Useful Lives in Years	20 years 6 months
Gross Book Value	$ 91,495	71,995
Accumulated Amortization	$ (18,661)	$ (15,281)
Trade Name \| Minimum
Identifiable Intangible Assets, Net
Estimated Useful Lives in Years	20 years 6 months
Customer Relationships Noncompete Agreements and Tradenames \| Minimum
Identifiable Intangible Assets, Net
Estimated Useful Lives in Years	1 year
Customer Relationships Noncompete Agreements and Tradenames \| Maximum
Identifiable Intangible Assets, Net
Estimated Useful Lives in Years	25 years

Goodwill and Identifiable Intangible Assets, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Asset Impairment Charges [Abstract]
Goodwill	$ 464,392	$ 332,447	$ 235,182
Impairment testing, Scenario one
Asset Impairment Charges [Abstract]
Impairment testing, discounted cash flow analysis weightage assigned		50.00%
Impairment testing, Scenario two
Asset Impairment Charges [Abstract]
Impairment testing, public company approach weightage assigned		50.00%
Walker
Asset Impairment Charges [Abstract]
Percentage of fair values in excess of carrying value of two acquired reporting units		27.00%
Percentage of fair values in excess of carrying value for Walker reporting unit	24.00%
Goodwill	$ 96,800

Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property and equipment
Property and equipment, gross	$ 264,408	$ 239,165
Less-Accumulated depreciation	(147,202)	(129,369)
Property and equipment, net	117,206	109,796
Depreciation expense	27,900	24,500	$ 22,600
Land
Property and equipment
Property and equipment, gross	7,167	6,206
Transportation equipment
Property and equipment
Property and equipment, gross	$ 113,802	106,972
Transportation equipment \| Minimum
Property and equipment
Estimated useful life	1 year
Transportation equipment \| Maximum
Property and equipment
Estimated useful life	7 years
Machinery and equipment
Property and equipment
Property and equipment, gross	$ 43,386	35,575
Machinery and equipment \| Minimum
Property and equipment
Estimated useful life	1 year
Machinery and equipment \| Maximum
Property and equipment
Estimated useful life	20 years
Computer and telephone equipment
Property and equipment
Property and equipment, gross	$ 23,215	20,744
Computer and telephone equipment \| Minimum
Property and equipment
Estimated useful life	1 year
Computer and telephone equipment \| Maximum
Property and equipment
Estimated useful life	10 years
Buildings and leasehold improvements
Property and equipment
Property and equipment, gross	$ 69,683	62,301
Buildings and leasehold improvements \| Minimum
Property and equipment
Estimated useful life	1 year
Buildings and leasehold improvements \| Maximum
Property and equipment
Estimated useful life	40 years
Furniture and fixtures
Property and equipment
Property and equipment, gross	$ 5,861	5,244
Furniture and fixtures \| Minimum
Property and equipment
Estimated useful life	1 year
Furniture and fixtures \| Maximum
Property and equipment
Estimated useful life	17 years
Construction in progress
Property and equipment
Property and equipment, gross	$ 1,294	$ 2,123

Detail of Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Other current liabilities
Accrued warranty costs	$ 8,914	$ 7,452
Current lease liability	16,586	14,016
Operating lease liability	97,162	86,713
Accrued job losses	2,151	2,226
Accrued sales and use tax	3,731	2,938
Deferred revenue	4,559	5,506
Liabilities due to former owners	10,280	11,219
Other current liabilities	45,271	38,273
Total other current liabilities	$ 91,492	$ 81,630

Debt Obligations (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Debt Obligations
Total principal amount	$ 236,000	$ 226,483
Less-unamortized debt issuance costs	(267)	(348)
Total debt, net of unamortized debt issuance costs	235,733	226,135
Less-current portion		20,817
Total long-term portion of debt, net	235,733	205,318
Revolving credit facility
Debt Obligations
Total principal amount	70,000	28,000
Term loan
Debt Obligations
Total principal amount	135,000	150,000
Notes to former owners
Debt Obligations
Outstanding balance	$ 31,000	$ 48,483

Debt Obligations - Future Payments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Future principal payments of long-term debt
2022	$ 23,000
2023	34,000
2023	26,500
2024	152,500
Total debt	236,000
Interest expense
Interest expense on notes to former owners	1,354	$ 1,531	$ 642
Interest expense on borrowings and unused commitment fees	5,319	6,887	2,211
Interest expense on interest rate swaps	338
Letter of credit fees	830	512	474
Amortization of debt financing costs	544	387	383
Total	$ 8,385	$ 9,317	$ 3,710

Debt Obligations - Other (Details) $ in Thousands				12 Months Ended
Debt Obligations - Other (Details) $ in Thousands	Dec. 31, 2019 USD ($)	Dec. 20, 2019 USD ($)	Dec. 19, 2019 USD ($)	Dec. 31, 2020 USD ($) item	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Debt Obligations
Payments on term loan				$ 15,000
Financing and professional cost					$ 1,405	$ 844
Outstanding balance	$ 226,483			236,000	226,483
Reconciliation of Credit Facility Adjusted EBITDA to net income
Net income				150,139	114,324	112,903
Provision for income taxes				41,401	37,418	35,773
Stock-based compensation				$ 6,934	5,878	$ 7,161
Principal financial covenants
Fixed charge coverage ratio				2.00
Other disclosures
2022				$ 23,000
2023				34,000
Revolving credit facility
Debt Obligations
Borrowing capacity		$ 450,000
Payments of financing costs line of credit arrangements	1,000
Outstanding borrowings				70,000
Outstanding balance	28,000			70,000	28,000
Letters of credit amount outstanding				49,500
Credit available				330,500
Book value of assets pledged as collateral				$ 167,800
Number of quarters of net earnings used for the calculation of the credit facility adjusted EBITDA \| item				4
Reconciliation of Credit Facility Adjusted EBITDA to net income
Net income				$ 150,139
Provision for income taxes				41,401
Interest expense, net				8,282
Depreciation and amortization expense				(60,629)
Stock-based compensation				6,934
Pre-acquisition results of acquired companies, as defined under the Facility				(18,511)
Credit Facility Adjusted EBITDA				$ 285,896
Principal financial covenants
Number of interest rate options \| item				2
Leverage ratio				0.8
Fixed charge coverage ratio				7.2
Number of quarters of capital expenditures, tax provision, dividends and stock repurchase payments used for calculation of fixed charge coverage ratio \| item				4
Period of Credit Facility Adjusted EBITDA for determining additional margins				12 months
Debt Instrument, Interest Rate, Effective Percentage [Abstract]
Weighted average interest rate (as a percent)				1.40%
Revolving credit facility \| Through maturity
Principal financial covenants
Leverage ratio				3.00
Revolving credit facility \| Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: Less than 1.00
Debt Instrument, Interest Rate, Effective Percentage [Abstract]
Letter of credit fees (as a percent)				1.25%
Commitment fees payable on unused portion of the facility (as a percent)				0.20%
Revolving credit facility \| Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 1.00 to 1.75
Debt Instrument, Interest Rate, Effective Percentage [Abstract]
Letter of credit fees (as a percent)				1.50%
Commitment fees payable on unused portion of the facility (as a percent)				0.25%
Revolving credit facility \| Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 1.75 to 2.50
Debt Instrument, Interest Rate, Effective Percentage [Abstract]
Letter of credit fees (as a percent)				1.75%
Commitment fees payable on unused portion of the facility (as a percent)				0.30%
Revolving credit facility \| Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 2.50 or greater
Debt Instrument, Interest Rate, Effective Percentage [Abstract]
Letter of credit fees (as a percent)				2.00%
Commitment fees payable on unused portion of the facility (as a percent)				0.35%
Revolving credit facility \| Minimum
Principal financial covenants
Fixed charge coverage ratio				1.50
Revolving credit facility \| Minimum \| Covenant Requirement
Principal financial covenants
Net leverage ratio used as basis for other restrictions				2.50
Revolving credit facility \| Maximum
Principal financial covenants
Permitted amount of acquisitions per transaction				$ 5,000
Aggregate purchase price of current acquisition and acquisitions in the preceding 12 month period for determining permitted amount of acquisition per transaction				$ 10,000
Revolving credit facility \| Base Rate \| Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: Less than 1.00
Debt Instrument, Interest Rate, Effective Percentage [Abstract]
Additional per annum interest margin (as a percent)				0.25%
Revolving credit facility \| Base Rate \| Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 1.00 to 1.75
Debt Instrument, Interest Rate, Effective Percentage [Abstract]
Additional per annum interest margin (as a percent)				0.50%
Revolving credit facility \| Base Rate \| Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 1.75 to 2.50
Debt Instrument, Interest Rate, Effective Percentage [Abstract]
Additional per annum interest margin (as a percent)				0.75%
Revolving credit facility \| Base Rate \| Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 2.50 or greater
Debt Instrument, Interest Rate, Effective Percentage [Abstract]
Additional per annum interest margin (as a percent)				1.00%
Revolving credit facility \| Eurodollar Rate \| Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: Less than 1.00
Debt Instrument, Interest Rate, Effective Percentage [Abstract]
Additional per annum interest margin (as a percent)				1.25%
Revolving credit facility \| Eurodollar Rate \| Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 1.00 to 1.75
Debt Instrument, Interest Rate, Effective Percentage [Abstract]
Additional per annum interest margin (as a percent)				1.50%
Revolving credit facility \| Eurodollar Rate \| Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 1.75 to 2.50
Debt Instrument, Interest Rate, Effective Percentage [Abstract]
Additional per annum interest margin (as a percent)				1.75%
Revolving credit facility \| Eurodollar Rate \| Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 2.50 or greater
Debt Instrument, Interest Rate, Effective Percentage [Abstract]
Additional per annum interest margin (as a percent)				2.00%
Amended senior revolving credit facility
Debt Obligations
Borrowing capacity		600,000	$ 400,000	$ 585,000
Line of credit borrowing capacity accordion option		150,000
Payments on term loan				15,000
Financing and professional cost	1,400
Unamortized costs			$ 1,300
Term loan
Debt Obligations
Borrowing capacity		$ 150,000
Repayment in terms of percentage of original aggregate principal amount		3.75%	1.25%
Payments of financing costs term loan	400
Outstanding balance	150,000			$ 135,000	150,000
Debt Instrument, Interest Rate, Effective Percentage [Abstract]
Weighted average interest rate (as a percent)				1.40%
Notes to former owners
Other disclosures
Cumulative number of companies acquired \| item				4
Outstanding balance	$ 48,483			$ 31,000	$ 48,483
Promissory note \| Walker
Other disclosures
Outstanding balance				$ 10,000
Stated interest rate (as a percent)				4.00%
Promissory note \| TAS Energy
Other disclosures
Outstanding balance				$ 8,000
Stated interest rate (as a percent)				3.50%
Promissory note \| T E C Industrial Construction and Maintenance
Other disclosures
Outstanding balance				$ 7,000
Stated interest rate (as a percent)				2.50%
Promissory note \| Electrical Contractor North Carolina
Other disclosures
Outstanding balance				$ 6,000
Stated interest rate (as a percent)				3.00%
Letter of Credit
Debt Obligations
Borrowing capacity		$ 160,000
Federal Funds Rate \| Revolving credit facility \| Base Rate
Market rates relating to interest options
Market rate (as a percent)				0.59%
Debt Instrument, Interest Rate, Effective Percentage [Abstract]
Additional per annum interest margin (as a percent)				0.50%
Wells Fargo Bank, N.A. Prime Rate \| Revolving credit facility \| Base Rate
Market rates relating to interest options
Market rate (as a percent)				3.25%
One-month LIBOR \| Revolving credit facility \| Base Rate
Market rates relating to interest options
Market rate (as a percent)				1.14%
Debt Instrument, Interest Rate, Effective Percentage [Abstract]
Additional per annum interest margin (as a percent)				1.00%
One-month LIBOR \| Revolving credit facility \| Eurodollar Rate
Market rates relating to interest options
Variable rate basis				One-month LIBOR
Market rate (as a percent)				0.14%
Six-month LIBOR \| Revolving credit facility \| Eurodollar Rate
Market rates relating to interest options
Variable rate basis				Six-month LIBOR
Market rate (as a percent)				0.26%

Leases (Details) $ in Millions	12 Months Ended
Leases (Details) $ in Millions	Dec. 31, 2020 USD ($) Option	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Lessee, Lease, Description [Line Items]
Variable lease expense and short-term lease expenses	$ 7.7	$ 8.4
Weighted average discount rate	4.20%	3.90%
Lease expense	$ 28.2	$ 24.8	$ 23.4
Weighted average remaining lease term	7 years 6 months	8 years 1 month 6 days
Rent paid to related parties	$ 4.2	$ 3.7	$ 4.8
Minimum
Lessee, Lease, Description [Line Items]
Lease term	3 years
Number of options to renew \| Option	1
Maximum
Lessee, Lease, Description [Line Items]
Lease term	10 years

Leases - Summary of Lease Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Summary of lease asset and liabilities
Lease right-of-use assets	$ 94,727	$ 84,073
Operating Lease, Liability [Abstract]
Other current liabilities	$ 16,586	$ 14,016
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Other current liabilities	Other current liabilities
Long-term lease liabilities	$ 80,576	$ 72,697
Operating Lease, Liability, Statement of Financial Position [Extensible List]	Long-term lease liabilities	Long-term lease liabilities
Present Value of Lease Liabilities	$ 97,162	$ 86,713

Leases - Maturities of Lease Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Maturities of lease liabilities:
2021	$ 20,254
2022	17,004
2023	14,727
2024	13,221
2024	12,108
Thereafter	36,645
Total Lease Payments	113,959
Less-Present Value Discount	(16,797)
Present Value of Lease Liabilities	97,162	$ 86,713
Supplemental information related to leases:
Cash paid for amounts included in the measurement of lease liabilities	20,443	16,895
Lease right-of-use assets obtained in exchange for lease liabilities	$ 27,346	$ 26,811

Income Taxes - Provision (Details) - USD ($) $ in Thousands	12 Months Ended
Income Taxes - Provision (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current tax provision-
Federal	$ 36,556	$ 33,281	$ 22,728
State and Puerto Rico	12,798	8,388	8,589
Total current	49,354	41,669	31,317
Deferred tax provision (benefit)-
Federal	(5,483)	(3,750)	4,347
State and Puerto Rico	(2,470)	(501)	109
Total deferred	(7,953)	(4,251)	4,456
Provision for income taxes	$ 41,401	$ 37,418	$ 35,773

- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References + Details

Income Taxes - Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Taxes
Effective tax rates on continuing operations		21.60%	24.70%	24.10%
Federal statutory income tax rate (as a percent)		21.00%	21.00%	21.00%
Income taxes at the federal statutory rate		$ 40,223	$ 31,866	$ 31,222
Increases (decreases) resulting from-
Net state income taxes		8,406	6,644	7,470
Valuation allowances		(254)	(279)	(2,852)
Net unrecognized tax benefits		18,557	7,338	(15)
Nondeductible expenses		2,470	2,180	1,926
R&D tax credits	$ (4,600)	(26,133)	(4,569)	(2,726)
179D deduction		(1,062)	(5,126)
Net operating loss carryforwards				2,225
Stock-based compensation deductions		(426)	(714)	(1,293)
Other		(380)	78	(184)
Provision for income taxes		$ 41,401	37,418	$ 35,773
179D deduction			$ (2,200)

Income Taxes - Provision Changes, Examination (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended			12 Months Ended
	Oct. 31, 2020	Sep. 30, 2020	Sep. 30, 2019	Mar. 31, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Taxes
Change in provision for income taxes				$ 2,800
R&D tax credits			$ 4,600		$ 26,133	$ 4,569	$ 2,726
Additions based on tax positions related to prior years	$ 26,400	$ 7,300			26,858	7,473	2,726
Net operating loss carryforwards							2,225
179D deduction						2,200
Reduced provision for income taxes		8,300			8,301
Provision for income taxes					$ 41,401	$ 37,418	$ 35,773
Internal Revenue Service (IRS)
Income Taxes
Refund claims allowed in Income tax examination		8,900
Tax Year 2016
Income Taxes
Provision for income taxes	6,100
Tax Year 2017
Income Taxes
Provision for income taxes	8,500
Tax Year 2018
Income Taxes
Provision for income taxes	11,900
Total Tax Years 2016-2018
Income Taxes
Provision for income taxes	$ 26,500
179D Deduction
Income Taxes
Reduced provision for income taxes		$ 1,000

Income Taxes - Deferred Tax Assets (Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets-
Accounts receivable and allowance for doubtful accounts	$ 2,186	$ 1,660
Stock-based compensation	2,791	2,561
Accrued liabilities and expenses	39,761	25,569
Lease liabilities	22,768	20,873
Net operating loss carryforwards	12,127	2,750
Intangible assets		7,988
Other	627	525
Subtotal	80,260	61,926
Valuation allowances	(514)	(369)
Total deferred tax assets	79,746	61,557
Property and equipment	(13,877)	(11,286)
Deferred tax liabilities	1,339	1,425
Lease right-of-use asset	(22,715)	(20,873)
Long-term contracts	(609)	(876)
Intangible assets	(242)
Goodwill	(11,615)	(6,020)
Other	(2,626)	(2,004)
Total deferred tax liabilities	(51,684)	(41,059)
Net deferred tax assets	28,062	20,498
Deferred income tax assets
Deferred tax assets	$ 29,401	$ 21,923

Income Taxes - Loss Carryforwards and Other (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended	12 Months Ended
	Oct. 31, 2020	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Apr. 01, 2020
Operating loss carryforwards
Federal deferred tax assets net operating loss carryforwards			$ 9,400
State deferred tax assets net operating loss carryforwards			2,700
Net deferred tax assets			79,746	$ 61,557
Reconciliation of the beginning and ending amount of unrecognized tax benefits, excluding accrued interest and penalties
Balance at beginning of year			10,199	2,966	$ 8,929
Additions based on tax positions related to prior years	$ 26,400	$ 7,300	26,858	7,473	2,726
Reductions for tax positions related to prior years				(240)	(8,689)
Reductions for settlements with tax authorities		(8,300)	(8,301)
Balance at end of year			28,756	10,199	2,966
Interest and penalties accrued			0	0	600
Reduced provision for income taxes		$ 8,300	8,301
Federal
Operating loss carryforwards
Net operating loss carryforwards			44,900			$ 53,200
State
Operating loss carryforwards
Net operating loss carryforwards			46,200			$ 6,500
Increase in valuation allowance			500
Net deferred tax assets			2,200
Maximum
Reconciliation of the beginning and ending amount of unrecognized tax benefits, excluding accrued interest and penalties
Decrease in unrecognized tax benefits			$ 28,800

Employee Benefit Plans (Details) $ in Millions	12 Months Ended
Employee Benefit Plans (Details) $ in Millions	Dec. 31, 2020 USD ($) item	Dec. 31, 2019 USD ($) item	Dec. 31, 2018 USD ($)
Employee Benefit Plans
Percentage of contributions of covered employees' salaries or wages	2.50%
Contribution	$ 16.3	$ 14.2	$ 10.8
Amount payable to plan	$ 0.5	$ 0.3
Number of employees who are union members \| item	6	7
Contributions made to multi-employer pension plans	$ 0.0	$ 0.0	$ 0.0
Period in which certain individuals are entitled to fixed annual payments	15 years
Maximum age under which certain individuals are entitled to fixed annual payments	65 years
Portion of benefits vesting after ten years of completed service (as a percent)	50.00%
Period of completed service over which 50% of benefits are vested	10 years
Portion of benefits vesting after fifteen years of completed service (as a percent)	75.00%
Period of completed service over which 75% of benefits are vested	15 years
Period of service over which benefits are fully vested	20 years
Unfunded benefit liability	$ 4.0	$ 4.1

Commitments and Contingencies - Other and Bonds (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($) item
Obligation to perform subcontract work \| Pending Litigation
Commitments and Contingencies
Letter of intent under dispute \| item	2
Damages stated	$ 9.0
Obligation to perform subcontract work \| Customer \| Pending Litigation
Commitments and Contingencies
Damages claimed	$ 15.0
Surety \| Minimum
Surety
Percentage of business which has required bonds	15.00%
Surety \| Maximum
Surety
Percentage of business which has required bonds	25.00%

Commitments and Contingencies - Self-Insurance (Details)	Dec. 31, 2020 USD ($) item
Self-Insurance
Amount of loss fully insured above per-incident deductible amount	$ 132,500,000
Amount of excess loss insurance covered	132,500,000
Workers' Compensation
Self-Insurance
Per incident deductible amount	250,000,000,000
Amount of loss fully insured above per-incident deductible amount	250,000,000,000
Employer's Liability
Self-Insurance
Per incident deductible amount	250,000,000,000
Employer's Liability \| Maximum
Self-Insurance
Amount of excess loss insurance covered	132,500,000
General Liability
Self-Insurance
Per incident deductible amount	250,000,000,000
Amount of loss fully insured above per-incident deductible amount	10,000,000.0
General Liability \| Maximum
Self-Insurance
Amount of excess loss insurance covered	132,500,000
Auto Liability
Self-Insurance
Per incident deductible amount	250,000,000,000
Amount of loss fully insured above per-incident deductible amount	10,000,000.0
Auto Liability \| Maximum
Self-Insurance
Amount of excess loss insurance covered	$ 132,500,000
Employee Medical
Self-Insurance
Number of medical plans \| item	3
Employee Medical - Plan One
Self-Insurance
Per person, per policy deductible amount	$ 350,000
Employee Medical - Plan Two
Self-Insurance
Per person, per policy deductible amount	350,000
Employee Medical - Plan Three
Self-Insurance
Per incident deductible amount	$ 350,000

Stockholders' Equity - Incentive and Other (Details) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions	12 Months Ended			165 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2020	Dec. 08, 2020	May 31, 2017	May 31, 2012	Mar. 29, 2007
Share Repurchase Program
Share repurchase	$ 30,120	$ 19,550	$ 28,533
2012 Equity Incentive Plan
Stockholders' Equity
Number of shares authorized and reserved for issuance							5.1
Number of shares available for issuance	2.9			2.9
2017 Omnibus Incentive Plan
Stockholders' Equity
Number of shares authorized and reserved for issuance						2.9
Number of shares available for issuance	2.0			2.0
Stock Repurchase Program 2007
Share Repurchase Program
Number of shares of outstanding common stock authorized to be acquired under a stock repurchase program					10.3			1.0
Additional number of shares authorized for repurchase					0.7
Share repurchase (in shares)	0.7			9.3
Average price (in dollars per share)	$ 43.99			$ 19.63
Repurchased carrying basis	$ 30,100			$ 30,100

Stockholders' Equity - Anti-Dilutive Stock Options (Details) - shares shares in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stock Options \| Maximum
Earnings Per Share
Anti-dilutive securities excluded from computation of earnings per share amount (in shares)	0.1	0.1	0.1

Stockholders' Equity - Number of Shares (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of the number of shares outstanding with the number of shares used in computing basic and diluted earnings per share
Common shares outstanding, end of period	36,188	36,658	36,894
Effect of using weighted average common shares outstanding	354	196	308
Shares used in computing earnings per share-basic	36,542	36,854	37,202
Effect of shares issuable under stock option plans based on the treasury stock method	123	204	283
Effect of restricted and contingently issuable shares	73	73	107
Shares used in computing earnings per share-diluted	36,738	37,131	37,592

- Definition

Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of contingently issuable shares. Contingently issuable shares are those shares that are issuable for little or no cash contingent on certain conditions being met.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 54
-URI http://asc.fasb.org/extlink&oid=121326447&loc=d3e2603-109256

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 44
-URI http://asc.fasb.org/extlink&oid=121326447&loc=d3e2062-109256

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 26
-URI http://asc.fasb.org/extlink&oid=121326447&loc=d3e1828-109256

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 53
-URI http://asc.fasb.org/extlink&oid=121326447&loc=d3e2600-109256

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 52
-URI http://asc.fasb.org/extlink&oid=121326447&loc=d3e2597-109256

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 48
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121326447&loc=d3e2538-109256

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 48
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121326447&loc=d3e2538-109256

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 23
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121326447&loc=d3e1757-109256

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 51
-URI http://asc.fasb.org/extlink&oid=121326447&loc=d3e2574-109256

+ Details

Stock-Based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stock-Based Compensation
Stock-based compensation expense	$ 6.9	$ 5.9	$ 7.2
Income tax benefit	$ 1.5	$ 1.3	1.5
Minimum
Stock-Based Compensation
Sum of age and years of service for accelerated vesting on retirement of certain stock options and restricted stock awards	75 years
Stock Options
Stock-Based Compensation
Vesting period	3 years
Shares
Outstanding at beginning of year (in shares)	382
Exercised (in shares)	(114)
Outstanding at end of year (in shares)	268	382
Options exercisable at end of year (in shares)	241
Weighted-Average Exercise Price
Outstanding at beginning of year (in dollars per share)	$ 27.06
Exercised (in dollars per share)	18.85
Outstanding at end of year (in dollars per share)	$ 30.53	$ 27.06
Other information
Intrinsic value of options exercised	$ 3.2	$ 3.5	$ 6.7
Weighted-average remaining contractual term of options exercisable	5 years 2 months 12 days
Aggregate intrinsic value of options exercisable	$ 5.7
Number of options that are vested and expected to vest (in shares)	300
Weighted average exercise price of options that are vested and expected to vest (in dollars per share)	$ 30.53
Weighted-average remaining contractual term of options that are vested and expected to vest	5 years 4 months 24 days
Aggregate intrinsic value of options that are vested and expected to vest	$ 5.9

Stock-Based Compensation - Stock Option Plan Activity (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2020 $ / shares shares
$11.21 - $15.00
Stock-Based Compensation
Exercise price, low end of range (in dollars per share)	$ 11.21
Exercise price, high end of range (in dollars per share)	15.00
$15.01 - $35.00
Stock-Based Compensation
Exercise price, low end of range (in dollars per share)	15.01
Exercise price, high end of range (in dollars per share)	35.00
$35.01 - $42.50
Stock-Based Compensation
Exercise price, low end of range (in dollars per share)	35.01
Exercise price, high end of range (in dollars per share)	42.50
$11.21 - $42.50
Stock-Based Compensation
Exercise price, low end of range (in dollars per share)	11.21
Exercise price, high end of range (in dollars per share)	$ 42.50
Stock Options \| $11.21 - $15.00
Options Outstanding
Number of Shares \| shares	14
Weighted-Average Remaining Contractual Life	2 years 2 months 12 days
Weighted-Average Exercise Price (in dollars per share)	$ 13.76
Options Exercisable
Number of Shares \| shares	14
Weighted-Average Exercise Price (in dollars per share)	$ 13.76
Stock Options \| $15.01 - $35.00
Options Outstanding
Number of Shares \| shares	130
Weighted-Average Remaining Contractual Life	4 years 4 months 24 days
Weighted-Average Exercise Price (in dollars per share)	$ 23.54
Options Exercisable
Number of Shares \| shares	130
Weighted-Average Exercise Price (in dollars per share)	$ 23.54
Stock Options \| $35.01 - $42.50
Options Outstanding
Number of Shares \| shares	124
Weighted-Average Remaining Contractual Life	6 years 9 months 18 days
Weighted-Average Exercise Price (in dollars per share)	$ 39.78
Options Exercisable
Number of Shares \| shares	97
Weighted-Average Exercise Price (in dollars per share)	$ 39.02
Stock Options \| $11.21 - $42.50
Options Outstanding
Number of Shares \| shares	268
Weighted-Average Remaining Contractual Life	5 years 4 months 24 days
Weighted-Average Exercise Price (in dollars per share)	$ 30.53
Options Exercisable
Number of Shares \| shares	241
Weighted-Average Exercise Price (in dollars per share)	$ 29.18

Stock-Based Compensation - Fair Value Assumptions (Details) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($) item $ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) $ / shares
Fair value assumptions:
Expected term			5 years 3 months 18 days
Additional information
Stock-based compensation expense \| $	$ 6.9	$ 5.9	$ 7.2
Stock Options
Stock-Based Compensation
Weighted-average fair value per share of options granted (in dollars per share)			$ 13.06
Fair value assumptions:
Expected dividend yield (as a percent)			0.79%
Expected stock price volatility (as a percent)			31.70%
Risk-free interest rate (as a percent)			2.66%
Other information
Compensation expense yet to be recognized \| $	$ 0.1
Weighted-average period over which compensation cost will be recognized	3 months 18 days
Total fair value of options vested \| $	$ 0.7
Nonvested Options, Shares
Nonvested at beginning of year (in shares) \| shares	81
Vested (in shares) \| shares	(54)
Nonvested at end of year (in shares) \| shares	27	81
Nonvested Options, Weighted-Average Grant Date Fair Value
Nonvested at beginning of year (in dollars per share)	$ 12.53
Granted (in dollars per share)			$ 13.06
Vested (in dollars per share)	12.26
Nonvested at end of year (in dollars per share)	$ 13.06	$ 12.53
Additional information
Vesting period	3 years
Restricted Stock and Restricted Stock Units
Other information
Compensation expense yet to be recognized \| $	$ 1.1
Weighted-average period over which compensation cost will be recognized	1 year 9 months 18 days
Shares
Unvested at beginning of year (in shares) \| shares	91
Granted (in shares) \| shares	118
Vested (in shares) \| shares	(85)
Forfeited (in shares) \| shares	(4)
Unvested at end of year (in shares) \| shares	120	91
Weighted Average Grant Date Fair Value
Unvested at beginning of year (in dollars per share)	$ 47.58
Granted (in dollars per share)	39.03	$ 51.02	44.02
Vested (in dollars per share)	39.13
Forfeited (in dollars per share)	45.21
Unvested at end of year (in dollars per share)	$ 45.21	47.58
Additional information
Fair value of shares vested \| $	$ 3.3
Weighted-average fair value (in dollars per share)	$ 39.03	$ 51.02	$ 44.02
Aggregate intrinsic value of restricted stock vested \| $	$ 2.9	$ 3.5	$ 3.3
Performance Stock Units
Other information
Compensation expense yet to be recognized \| $	$ 0.7
Weighted-average period over which compensation cost will be recognized	1 year 4 months 24 days
Additional information
Vesting period	3 years
Types of performance units \| item	2
Percentage of units measured on stock price relative to peer group	50.00%
Percentage of units measured on stock price based on pre determined EPS	50.00%
Period for which shareholder return is compared with peer group for units determined by EPS performance	3 years
Calculated fair market value \| $	$ 6.2
Value of PSUs granted \| $	2.2
Stock-based compensation expense \| $	$ 2.7	$ 1.9	$ 2.9
Performance Stock Units \| Minimum
Additional information
Performance measures for dollar denominated award granted	0
Performance Stock Units \| Maximum
Additional information
Performance measures for dollar denominated award granted	2.0

Segment Information (Details) $ in Thousands	3 Months Ended								12 Months Ended
Segment Information (Details) $ in Thousands	Dec. 31, 2020 USD ($)	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2020 USD ($) segment	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Segment Information
Number of reportable segments \| segment									2
Revenue	$ 698,961	$ 714,099	$ 743,468	$ 700,131	$ 719,584	$ 706,918	$ 650,302	$ 538,473	$ 2,856,659	$ 2,615,277	$ 2,182,879
Gross Profit	136,999	$ 147,196	$ 145,695	$ 117,093	132,560	$ 142,702	$ 120,016	$ 106,665	546,983	501,943	446,279
Capital Expenditures									24,131	31,750	27,268
Total Assets	1,757,355				1,505,012				1,757,355	1,505,012
Operating \| Mechanical Services
Segment Information
Revenue									2,413,016	2,251,560	2,176,223
Gross Profit									509,740	465,144	444,960
Capital Expenditures									22,550	27,933	25,945
Total Assets	1,215,985				1,056,609				1,215,985	1,056,609
Operating \| Electrical Services
Segment Information
Revenue									443,643	363,717	6,656
Gross Profit									37,243	36,799	1,319
Capital Expenditures									955	1,504	57
Total Assets	449,588				372,254				449,588	372,254
Corporate & Eliminations
Segment Information
Capital Expenditures									626	2,313	$ 1,266
Total Assets	$ 91,782				$ 76,149				$ 91,782	$ 76,149

Selected Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Selected Quarterly Financial Data
Revenue	$ 698,961	$ 714,099	$ 743,468	$ 700,131	$ 719,584	$ 706,918	$ 650,302	$ 538,473	$ 2,856,659	$ 2,615,277	$ 2,182,879
Gross Profit	136,999	147,196	145,695	117,093	132,560	142,702	120,016	106,665	546,983	501,943	446,279
Net income	$ 42,840	$ 50,088	$ 39,495	$ 17,716	$ 34,052	$ 36,233	$ 24,173	$ 19,866	$ 150,139	$ 114,324	$ 112,903
Basic-
Basic (in dollars per share)	$ 1.18	$ 1.37	$ 1.08	$ 0.48	$ 0.93	$ 0.98	$ 0.65	$ 0.54	$ 4.11	$ 3.10	$ 3.03
Diluted-
Diluted (in dollars per share)	$ 1.17	$ 1.36	$ 1.08	$ 0.48	$ 0.92	$ 0.98	$ 0.65	$ 0.53	$ 4.09	$ 3.08	$ 3.00
Gain due to insurance proceeds received					$ 4,800

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22583-107794

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 11
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22694-107794

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=121326447&loc=d3e1448-109256

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22595-107794

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 11
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22694-107794

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=121326447&loc=d3e1337-109256

Reference 7: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 55
-Paragraph 52
-URI http://asc.fasb.org/extlink&oid=120380238&loc=d3e4984-109258

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(23))
-URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 55
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=120380238&loc=d3e3842-109258

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22644-107794

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(25))
-URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=121326447&loc=d3e1252-109256

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 60B
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121326447&loc=SL5780133-109256

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(27))
-URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260

+ Details

- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 55
-Paragraph 52
-URI http://asc.fasb.org/extlink&oid=120380238&loc=d3e4984-109258

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22644-107794

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 55
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=120380238&loc=d3e3842-109258

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=121326447&loc=d3e1252-109256

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 11
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22694-107794

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22595-107794

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22583-107794

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 60B
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121326447&loc=SL5780133-109256

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(27))
-URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(23))
-URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 11
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22694-107794

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=121326447&loc=d3e1337-109256

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(25))
-URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227

+ Details

- Definition

Aggregate revenue less cost of goods and services sold or operating expenses directly attributable to the revenue generation activity.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 31
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8924-108599

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8906-108599

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(g)(1)(ii))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 28
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=75031198&loc=d3e14064-108612

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1,2)
-URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

+ Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 1A
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121641772&loc=SL7669619-108580

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 31
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8924-108599

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 11
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22694-107794

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(22))
-URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 11
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22694-107794

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=109222650&loc=SL51721683-107760

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22595-107794

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 1B
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121641772&loc=SL7669625-108580

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 11: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(18))
-URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263

Reference 12: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(20))
-URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227

Reference 13: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22499-107794

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22663-107794

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 28
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=75031198&loc=d3e14064-108612

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8906-108599

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22583-107794

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(g)(1)(ii))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

Reference 20: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 60B
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121326447&loc=SL5780133-109256

Reference 21: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

Reference 22: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 23: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22658-107794

+ Details

- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 28
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=75031198&loc=d3e14064-108612

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 40
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9031-108599

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8906-108599

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9038-108599

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9054-108599

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(g)(1)(ii))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 235
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-05(b)(2))
-URI http://asc.fasb.org/extlink&oid=120399901&loc=d3e537907-122884

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(1))
-URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227

+ Details