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Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2016	Feb. 16, 2017	Jun. 30, 2016
Document and Entity Information
Entity Registrant Name	COMFORT SYSTEMS USA INC
Entity Central Index Key	0001035983
Document Type	10-K
Document Period End Date	Dec. 31, 2016
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 1,190
Entity Common Stock, Shares Outstanding		37,209,114
Document Fiscal Year Focus	2016
Document Fiscal Period Focus	FY

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
CURRENT ASSETS:
Cash and cash equivalents	$ 32,074	$ 56,464
Accounts receivable, less allowance for doubtful accounts of $4,288 and $5,158, respectively	318,837	302,052
Other receivables	20,363	20,642
Inventories	9,208	7,941
Prepaid expenses and other	6,106	5,836
Costs and estimated earnings in excess of billings	29,369	31,338
Total current assets	415,957	424,273
PROPERTY AND EQUIPMENT, NET	68,195	60,813
GOODWILL	149,208	143,874
IDENTIFIABLE INTANGIBLE ASSETS, NET	42,435	41,079
DEFERRED INCOME TAX ASSETS	27,170	16,276
OTHER NONCURRENT ASSETS	5,938	5,279
Total assets	708,903	691,594
CURRENT LIABILITIES:
Current maturities of long-term debt	600	500
Current maturities of long-term capital lease obligations	163	251
Accounts payable	103,440	106,684
Accrued compensation and benefits	61,712	54,079
Billings in excess of costs and estimated earnings	83,985	85,397
Accrued self-insurance	33,520	29,803
Other current liabilities	34,261	28,677
Total current liabilities	317,681	305,391
LONG-TERM DEBT	1,955	10,500
LONG-TERM CAPITAL LEASE OBLIGATIONS	93	256
DEFERRED INCOME TAX LIABILITIES	2,289	1,810
OTHER LONG-TERM LIABILITIES	10,252	8,632
Total liabilities	332,270	326,589
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, 3,914,251 and 3,696,781 shares, respectively	(57,387)	(46,845)
Additional paid-in capital	309,625	323,765
Retained earnings	123,984	69,390
Comfort Systems USA, Inc. stockholders' equity	376,633	346,721
Noncontrolling interests		18,284
Total stockholders' equity	376,633	365,005
Total liabilities and stockholders' equity	$ 708,903	$ 691,594

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
CONSOLIDATED BALANCE SHEETS
Accounts receivable, allowance for doubtful accounts (in dollars)	$ 4,288	$ 5,158
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	3,914,251	3,696,781

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
CONSOLIDATED STATEMENTS OF OPERATIONS
REVENUE	$ 1,634,340	$ 1,580,519	$ 1,410,795
COST OF SERVICES	1,290,331	1,262,390	1,161,024
Gross profit	344,009	318,129	249,771
SELLING, GENERAL AND ADMINISTRATIVE EXPENSES	243,201	228,965	207,652
GOODWILL IMPAIRMENT			727
GAIN ON SALE OF ASSETS	(761)	(880)	(830)
Operating income	101,569	90,044	42,222
OTHER INCOME (EXPENSE):
Interest income	9	72	18
Interest expense	(2,345)	(1,753)	(1,858)
Changes in the fair value of contingent earn-out obligations	731	225	(245)
Other	1,097	76	91
Other income (expense)	(508)	(1,380)	(1,994)
INCOME BEFORE INCOME TAXES	101,061	88,664	40,228
INCOME TAX EXPENSE	36,165	31,224	11,614
INCOME FROM CONTINUING OPERATIONS	64,896	57,440	28,614
Loss from discontinued operations, net of income tax benefit of $—, $— and $10			(15)
NET INCOME INCLUDING NONCONTROLLING INTERESTS	64,896	57,440	28,599
Less: Net income attributable to noncontrolling interests		8,076	5,536
NET INCOME ATTRIBUTABLE TO COMFORT SYSTEMS USA, INC.	$ 64,896	$ 49,364	$ 23,063
Basic-
Income from continuing operations (in dollars per share)	$ 1.74	$ 1.32	$ 0.61
Net income (in dollars per share)	1.74	1.32	0.61
Diluted-
Income from continuing operations (in dollars per share)	1.72	1.30	0.61
Net income (in dollars per share)	$ 1.72	$ 1.30	$ 0.61
SHARES USED IN COMPUTING INCOME PER SHARE:
Basic (in shares)	37,335	37,442	37,547
Diluted (in shares)	37,811	37,868	37,797
DIVIDENDS PER SHARE (in dollars per share)	$ 0.275	$ 0.250	$ 0.225

CONSOLIDATED STATEMENTS OF OPERATIONS (Parenthetical) $ in Thousands	12 Months Ended
	Dec. 31, 2014 USD ($)
CONSOLIDATED STATEMENTS OF OPERATIONS
Operating loss, income tax benefit	$ 10

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Treasury Stock	Additional Paid-In Capital	Retained Earnings	Non-Controlling Interests	Total
BALANCE at Dec. 31, 2013	$ 411	$ (37,468)	$ 318,123	$ 14,768	$ 18,188	$ 314,022
BALANCE (in shares) at Dec. 31, 2013	41,123,365
BALANCE (in shares) at Dec. 31, 2013		3,488,438
Increase (Decrease) in Stockholders' Equity
Net income				23,063	5,536	28,599
Issuance of Stock:
Issuance of shares for options exercised		$ 1,132	79			1,211
Issuance of shares for options exercised including tax benefit (in shares)		103,619
Issuance of restricted stock		$ 1,243	(1,243)
Issuance of restricted stock (in shares)		115,044
Shares received in lieu of tax withholding payment on vested restricted stock		$ (531)				(531)
Shares received in lieu of tax withholding payment on vested restricted stock (in shares)		(34,657)
Tax benefit from vesting of restricted stock			133			133
Stock-based compensation			2,992			2,992
Dividends				(8,447)		(8,447)
Distribution to noncontrolling interests					(8,612)	(8,612)
Share repurchase		$ (7,974)				(7,974)
Share repurchase (in shares)		(549,154)
BALANCE at Dec. 31, 2014	$ 411	$ (43,598)	320,084	29,384	15,112	$ 321,393
BALANCE (in shares) at Dec. 31, 2014	41,123,365					37,270,000
BALANCE (in shares) at Dec. 31, 2014		3,853,586
Increase (Decrease) in Stockholders' Equity
Net income				49,364	8,076	$ 57,440
Issuance of Stock:
Issuance of shares for options exercised		$ 3,728	966			4,694
Issuance of shares for options exercised including tax benefit (in shares)		317,333
Issuance of restricted stock & performance stock		$ 2,292	(626)			1,666
Issuance of restricted stock & performance stock (in shares)		200,015
Shares received in lieu of tax withholding payment on vested restricted stock		$ (937)				(937)
Shares received in lieu of tax withholding payment on vested restricted stock (in shares)		(44,590)
Tax benefit from vesting of restricted stock			284			284
Stock-based compensation			3,057			3,057
Dividends				(9,358)		(9,358)
Distribution to noncontrolling interests					(4,904)	(4,904)
Share repurchase		$ (8,330)				(8,330)
Share repurchase (in shares)		(315,953)
BALANCE at Dec. 31, 2015	$ 411	$ (46,845)	323,765	69,390	18,284	$ 365,005
BALANCE (in shares) at Dec. 31, 2015	41,123,365					37,427,000
BALANCE (in shares) at Dec. 31, 2015		3,696,781				(3,696,781)
Increase (Decrease) in Stockholders' Equity
Net income				64,896		$ 64,896
Issuance of Stock:
Issuance of shares for options exercised		$ 1,568	10			1,578
Issuance of shares for options exercised including tax benefit (in shares)		111,761
Issuance of restricted stock & performance stock		$ 2,282	(306)			1,976
Issuance of restricted stock & performance stock (in shares)		172,727
Shares received in lieu of tax withholding payment on vested restricted stock		$ (1,304)				(1,304)
Shares received in lieu of tax withholding payment on vested restricted stock (in shares)		(41,788)
Stock-based compensation			3,502			3,502
Dividends				(10,264)		(10,264)
Share repurchase		$ (13,088)				(13,088)
Share repurchase (in shares)		(460,170)
Acquisition of noncontrolling interests			(17,346)		$ (18,284)	(35,630)
BALANCE at Dec. 31, 2016	$ 411	$ (57,387)	$ 309,625	123,984		$ 376,633
BALANCE (in shares) at Dec. 31, 2016	41,123,365					37,209,000
BALANCE (in shares) at Dec. 31, 2016		3,914,251				(3,914,251)
Increase (Decrease) in Stockholders' Equity
Cumulative effect of change in accounting principle (unaudited)				$ (38)		$ (38)

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income including noncontrolling interests	$ 64,896	$ 57,440	$ 28,599
Adjustments to reconcile net income to net cash provided by operating activities
Amortization of identifiable intangible assets	8,185	7,481	7,653
Depreciation expense	17,981	15,935	13,683
Goodwill impairment			727
Bad debt expense (benefit)	(27)	1,552	1,275
Deferred tax expense (benefit)	(1,239)	(414)	(4,579)
Amortization of debt financing costs	367	317	283
Gain on sale of assets	(761)	(880)	(830)
Changes in the fair value of contingent earn-out obligations	(731)	(225)	245
Stock-based compensation expense	5,041	5,609	4,806
(Increase) decrease in-
Receivables, net	7,038	(3,584)	(18,339)
Inventories	213	956	281
Prepaid expenses and other current assets	(8,850)	364	1,494
Costs and estimated earnings in excess of billings	3,144	(3,630)	2,744
Other noncurrent assets	(143)	(479)	(321)
Increase (decrease) in-
Accounts payable and accrued liabilities	2,736	11,617	(4,078)
Billings in excess of costs and estimated earnings	(8,351)	7,908	7,545
Other long-term liabilities	1,689	(2,100)	1,364
Net cash provided by operating activities	91,188	97,867	42,552
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(23,217)	(20,808)	(19,183)
Proceeds from sales of property and equipment	1,062	1,338	1,355
Cash paid for acquisitions, net of cash acquired	(57,163)	(6,158)	(56,314)
Net cash used in investing activities	(79,318)	(25,628)	(74,142)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from revolving line of credit	144,000	24,500	128,500
Payments on revolving line of credit	(154,000)	(53,000)	(90,000)
Payments on other debt	592		2,000
Payments on capital lease obligations	(251)	(443)	(115)
Debt financing costs	(789)		(568)
Payments of dividends to shareholders	(10,264)	(9,358)	(8,444)
Share repurchase	(13,088)	(8,330)	(7,974)
Shares received in lieu of tax withholding	(1,304)	(937)	(531)
Excess tax benefit of stock-based compensation		1,240	115
Proceeds from exercise of options	1,578	3,738	1,229
Distributions to noncontrolling interests		(4,904)	(8,612)
Deferred acquisition payments	(1,350)
Payments for contingent consideration arrangements	(200)	(345)
Net cash provided by (used in) financing activities	(36,260)	(47,839)	11,600
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(24,390)	24,400	(19,990)
CASH AND CASH EQUIVALENTS, beginning of period	56,464	32,064	52,054
CASH AND CASH EQUIVALENTS, end of period	$ 32,074	$ 56,464	$ 32,064

Business and Organization

12 Months Ended

Dec. 31, 2016

Business and Organization

Business and Organization

1. Business and Organization

Comfort Systems USA, Inc., a Delaware corporation, provides comprehensive mechanical contracting services, which principally includes heating, ventilation and air conditioning (“HVAC”), plumbing, piping and controls, as well as off-site construction, electrical, monitoring and fire protection. We install, maintain, repair and replace products and systems throughout the United States. Approximately 40% of our consolidated 2016 revenue is attributable to installation of systems in newly constructed facilities, with the remaining 60% attributable to maintenance, repair and replacement services.

Our consolidated 2016 revenue was derived from the following service activities, all of which are in the mechanical services industry, the single industry segment we serve:


	Revenue
Service Activity	$ in thousands		%
HVAC	$	1,225,755	75	%
Plumbing		245,151	15	%
Building Automation Control Systems		98,060	6	%
Other		65,374	4	%
Total	$	1,634,340	100	%

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2016

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, the allowance for doubtful accounts, self‑insurance accruals, deferred tax assets, warranty accruals, fair value accounting for acquisitions and the quantification of fair value for reporting units in connection with our goodwill impairment testing. In 2015, two operating locations came to an agreement with customers on multiple jobs and received approved change orders, which resulted in the recognition of additional revenue with minimal additional costs resulting in a project gain of $3.4 million, on a pre-tax basis. In the twelve months ended December 31, 2014, one of our operating locations recorded a revision in contract estimate on a project in a loss position resulting in a writedown to this individual project of $4.4 million, on a pre-tax basis.

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,
	2016		2015		2014
Interest	$	1,864	$	1,408	$	1,764
Income taxes	$	29,349	$	35,538	$	15,366

Recent Accounting Pronouncements

In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09, “Revenue from Contracts with Customers (Topic 606).” ASU 2014-09 provides a framework that replaces the existing revenue recognition guidance. The guidance can be applied on a full retrospective or modified retrospective basis whereby the entity records a cumulative effect of initially applying this update on the adoption date. We currently plan to use the modified retrospective basis on the adoption date. ASU 2014-09 is effective for annual periods beginning after December 15, 2017, including interim periods within that reporting period. While we are still evaluating the potential impact of this authoritative guidance on our consolidated financial statements, we currently believe the areas that may impact us the most include accounting for variable consideration, capitalization of incremental costs of obtaining a contract and the guidance on the number of performance obligations contained in a contract. The impact on our consolidated financial statements upon adoption of ASU 2014-09 will be determined in large part by the contracts in progress on our adoption date; however, we currently do not believe the adoption will have a material impact on our consolidated financial statements.

In April 2015, the FASB issued ASU No. 2015-03, “Simplifying the Presentation of Debt Issue Costs.” Under ASU 2015-03, an entity presents debt issue costs related to a note in the balance sheet as a direct deduction from the related debt liability rather than as an asset. Entities would apply the new guidance retrospectively to all prior periods. In August 2015, the FASB issued ASU No. 2015-15, “Presentation and Subsequent Measurement of Debt Issuance Costs Associated with Line-of-Credit Arrangements.” The amendment clarifies ASU 2015-03 and provides that an entity may defer and present debt issuance costs for a line-of-credit or other revolving credit facility arrangement as an asset and subsequently amortize the deferred debt issuance costs ratably over the term of the arrangement, regardless of whether there are any outstanding borrowings on the arrangement. As such, we will continue to include debt issuance costs for our revolving credit facility arrangements in other noncurrent assets. These ASUs are effective for annual periods beginning after December 15, 2015, including interim periods within that reporting period. We early adopted these ASUs on December 31, 2015, which did not have a material impact on our consolidated financial statements.

In July 2015, the FASB issued ASU No. 2015-11, "Simplifying the Measurement of Inventory", which requires that inventory within the scope of the guidance be measured at the lower of cost and net realizable value. Net realizable value is the estimated selling prices in the ordinary course of business, less reasonable predictable costs of completion, disposal and transportation. Inventory measured using last-in, first-out (LIFO) and the retail inventory method (RIM) are not impacted by the new guidance. Entities should apply the new guidance prospectively with earlier application permitted as of the beginning of an interim or annual reporting period. It is effective for fiscal years beginning after December 15, 2016, including interim periods within those fiscal years. We early adopted this ASU on December 31, 2016, which did not have a material impact on our consolidated financial statements.

In September 2015, the FASB issued ASU No. 2015-16, "Simplifying the Accounting for Measurement-Period Adjustments", which eliminates the requirement for an acquirer in a business combination to account for measurement-period adjustments retrospectively. Instead, acquirers must recognize measurement-period adjustments during the period in which they determine the amounts, including the effect on earnings of any amounts they would have recorded in previous periods if the accounting had been completed at the acquisition date. It is effective for fiscal years beginning after December 15, 2015, including interim periods within those fiscal years. We early adopted this ASU in the third quarter of 2015 and its adoption did not have a material impact on our consolidated financial statements.

In February 2016, the FASB issued ASU No. 2016-02, “Leases (Topic 842)”. The standard requires lessees to recognize assets and liabilities for most leases. ASU 2016-02 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2018. Early adoption is permitted. ASU 2016-02’s transition provisions are applied using a modified retrospective approach at the beginning of the earliest comparative period presented in the financial statements. Full retrospective application is prohibited. We are currently evaluating the potential impact of this authoritative guidance on our consolidated financial statements.

In March 2016, the FASB issued ASU No. 2016-09, “Compensation—Stock Compensation (Topic 718)”. The standard changes certain aspects of accounting for share-based payments to employees. Specifically, the new guidance requires excess tax benefits and tax deficiencies to be recognized in the income statement instead of additional paid-in capital when the awards vest or are settled. Additionally, cash flows related to excess tax benefits will be presented as an operating activity rather than a financing activity. ASU 2016-09 also allows an employer to repurchase more of an employee’s shares than it previously could for tax withholding purposes without triggering liability accounting and to make a policy election to account for forfeitures as they occur. ASU 2016-09 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2016. Early adoption is permitted, but all of the guidance must be adopted in the same period.

We elected to early adopt ASU 2016-09 in the second quarter of 2016, which required us to reflect any adjustments as of January 1, 2016. The primary impact of adoption was the recognition of $0.1 million of excess tax benefits in our provision for income taxes rather than additional paid-in capital. We elected to account for forfeitures as they occur to determine the amount of compensation cost to be recognized. The impact of this change in accounting policy was less than $0.1 million and was recorded as a cumulative effect adjustment to retained earnings for the increase to stock compensation expense. Amendments to the accounting for minimum statutory withholding tax requirements had no impact to retained earnings as of January 1, 2016.

We elected to apply the presentation requirements for cash flows related to excess tax benefits prospectively, which resulted in an increase to net cash provided by operations and a decrease to net cash provided by financing of $0.1 million for the three months ended March 31, 2016. The presentation requirements for cash flows related to employee taxes paid for withheld shares had no impact to our consolidated cash flow statement as such cash flows have historically been presented as a financing activity.

In August 2016, the FASB issued ASU No. 2016-15, “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments”. This standard provides guidance on how certain cash receipts and cash payments are presented and classified in the statement of cash flows and is intended to reduce diversity in practice with respect to these items. The standard is applied using a retrospective transition method and is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Early adoption is permitted. We are currently evaluating the potential impact of this authoritative guidance on our consolidated financial statements.

In January 2017, the FASB issued ASU No. 2017-04, “Intangibles – Goodwill and other (Topic 350): Simplifying the Accounting for Goodwill Impairment”. This standard removes Step 2 of the goodwill impairment test, which required a hypothetical purchase price allocation. A goodwill impairment will now be the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. Additionally, entities will be required to disclose the amount of goodwill at reporting units with zero or negative carrying amounts. The standard is applied prospectively and is effective for fiscal years beginning after December 15, 2019, including annual or interim goodwill impairment tests within those fiscal years. Early adoption is permitted for interim and annual goodwill impairment tests performed on testing dates after January 1, 2017. We plan to early adopt ASU 2017-04 in the first quarter of 2017.

Revenue Recognition

Approximately 82% of our revenue was earned on a project basis and recognized through the percentage of completion method of accounting. Under this method, 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 in connection with obtaining installation contracts, we estimate our contract costs, which include all direct materials (exclusive of rebates), 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, but is generally subjected to approval as to milestones or other evidence of completion. 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 not significant and 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.

We generally do not incur significant costs prior to receiving a contract, and therefore, these costs are expensed as incurred. In limited circumstances, when significant pre‑contract costs are incurred, they are deferred if the costs can be directly associated with a specific contract and if their recoverability from the contract is probable. Upon receiving the contract, these costs are included in contract costs. Deferred costs associated with unsuccessful contract bids are written off in the period that we are informed that we will not be awarded the contract.

Project contracts typically provide for a schedule of billings or invoices to the customer based on reaching agreed upon milestones or as we incur costs. The schedules for such billings usually do not precisely match the schedule on which costs are incurred. As a result, contract revenue recognized in the 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 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,
	2016		2015
Costs incurred on contracts in progress	$	1,116,182	$	1,135,279
Estimated earnings, net of losses		207,252		188,243
Less—Billings to date		(1,378,050)		(1,377,581)
	$	(54,616)	$	(54,059)
Costs and estimated earnings in excess of billings	$	29,369	$	31,338
Billings in excess of costs and estimated earnings		(83,985)		(85,397)
	$	(54,616)	$	(54,059)

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, 2016 and 2015 were $60.7 million and $51.6 million, respectively, and are included in accounts receivable.

Accounts payable at December 31, 2016 and 2015 included $10.1 million and $7.8 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 the 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 a 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 the customer agrees to pay additional 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, 2016.

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.

Revenue associated with maintenance, repair and monitoring services and related contracts are recognized as services are performed. Amounts associated with unbilled service work orders are reflected as a current asset in our balance sheet under the caption “Costs and estimated earnings in excess of billings” and amounts billed in advance of work orders being performed are reflected as a current liability in our balance sheet under the caption “Billings in excess of costs and estimated earnings.”

Accounts Receivable

The carrying value of our receivables, net of the allowance for doubtful accounts, represents the estimated net realizable value. We estimate our allowance for doubtful accounts based upon the creditworthiness of our customers, prior collection history, ongoing relationships with our customers, the aging of past due balances, our lien rights, if any, in the property where we performed the work and the availability, if any, of payment bonds applicable to the contract. The receivables are written off when they are deemed to be uncollectible.

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, an impairment loss is recorded to the extent that the implied fair value of the goodwill of the reporting unit is less than its carrying value. If other reporting units have had increases in fair value, such increases may not be recorded. Accordingly, such increases may not be netted against impairments at other reporting units. 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. Each of our operating units represents an operating segment, and our operating segments are our 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, then we perform the first step of a two‑step impairment test by calculating the fair value of the reporting unit and comparing 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 utilized 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, 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.

Long‑Lived Assets

Long‑lived assets are comprised principally of goodwill, identifiable intangible assets, property and equipment, and deferred income 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 can be determined. If the fair values of such contingencies cannot be determined, they are recognized at the acquisition date if the contingencies are probable and an amount can be reasonably estimated. 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 12 “Commitments and Contingencies.”

Warranty Costs

We typically warrant labor for the first year after installation on new HVAC systems. We generally warrant labor for thirty days after servicing of existing HVAC 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 are subject to income tax in the United States and Puerto Rico and file a consolidated return for federal income tax purposes. 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 income taxes are based on the difference between the financial reporting and tax basis of assets and liabilities. The deferred income 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 that 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. We perform this evaluation quarterly. In assessing the realizability of deferred tax assets, we must consider whether it is more likely than not that 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 of income tax expense in our Consolidated Statements of Operations.

Segment Disclosure

Our activities are within the mechanical services industry, which is the single industry segment we serve. Each operating unit represents an operating segment and these segments have been aggregated, as the operating units meet all of the aggregation criteria.

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 in 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 no single customer accounting for more than 3% of consolidated 2016 revenue.

Financial Instruments

Our financial instruments consist of cash and cash equivalents, accounts receivable, other receivables, accounts payable, life insurance policies, notes to former owners, capital leases, and a revolving credit facility. We believe that the carrying values of these instruments on the accompanying balance sheets approximate their fair values.

Fair Value Measurements

12 Months Ended

Dec. 31, 2016

Fair Value Measurements

Fair Value Measurements

3. Fair Value Measurements

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, 2016 (in thousands):



	Balance		Fair Value Measurements at Reporting Date
	December 31,
	2016		Level 1		Level 2		Level 3
Cash and cash equivalents	$	32,074	$	32,074	$	—	$	—
Life insurance—cash surrender value	$	3,697	$	—	$	3,697	$	—
Contingent earn-out obligations	$	2,531	$	—	$	—	$	2,531

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.

One of our operations has life insurance policies covering 48 employees with a combined face value of $44.2 million. The policies are invested in mutual funds 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 is $3.7 million as of December 31, 2016 and $3.6 million as of December 31, 2015. 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.

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).


Balance at beginning of year	$	450
Issuances		3,240
Settlements		(428)
Adjustments to fair value		(731)
Balance at December 31, 2016	$	2,531

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, 2016 or 2015. During the year ended December 31, 2014, we recorded a goodwill impairment charge of $0.7 million based on Level 3 measurements. See Note 6 “Goodwill and Identifiable Intangible Assets, Net” for further discussion. We did not recognize any other impairments on those assets required to be measured at fair value on a nonrecurring basis.

- 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
Acquisitions	Dec. 31, 2016
Acquisitions
Acquisitions	4. Acquisitions We completed two acquisitions in the first quarter of 2016. We acquired the remaining 40% noncontrolling interest in Environmental Air Systems, LLC (“EAS”) on January 1, 2016 for $46.6 million, including $42.0 million funded on the closing date plus a holdback, an earn-out that we will pay if certain financial targets are met after the acquisition date and a working capital adjustment. Due to our majority ownership and control over EAS on the acquisition date, the difference between the purchase price and the noncontrolling interest liability was recorded in Additional Paid-In Capital in our Balance Sheet. Additionally in the first quarter of 2016, we acquired 100% of the ShoffnerKalthoff family of companies (collectively, “Shoffner”), which reports as a separate operating location in the Knoxville, Tennessee area. Shoffner was included in our consolidated results of operations beginning on its acquisition date, which included revenue of $71.9 million. The acquisition date fair value of consideration transferred for this acquisition was $19.8 million, of which $14.8 million was allocated to goodwill and identifiable intangible assets. The purchase price included $15.5 million funded on the closing date plus a note payable to former owners, an earn-out that we will pay if certain financial targets are met after the acquisition date and a working capital adjustment. The acquisitions completed in the current year were not material, individually or in the aggregate. Other Acquisitions We completed various other acquisitions in 2016 and 2015 which were not material, individually or in the aggregate, and were “tucked-in” with existing operations. The total purchase price for the “tucked-in” acquisitions, including earn-outs, was $0.1 million in 2016 and $8.3 million in 2015. The results of operations of acquisitions are included in our consolidated financial statements from their respective acquisition dates. Additional contingent purchase price (“earn-out”) has been or will be paid if certain acquisitions achieve predetermined profitability targets. Such earn-outs are not subject to the continued employment of the sellers.

- Definition

The entire disclosure for a business combination (or series of individually immaterial business combinations) completed during the period, including background, timing, and recognized assets and liabilities. The disclosure may include leverage buyout transactions (as applicable).

+ References

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+ Details

Discontinued Operations

12 Months Ended

Dec. 31, 2016

Discontinued Operations

Discontinued Operations

5. Discontinued Operations

During the fourth quarter of 2012, we substantially completed the shutdown of our operation located in Delaware, which we decided to curtail operating in the fourth quarter of 2011. No activity was reported for the year ended December 31, 2016 or for the year ended December 31, 2015. The after tax loss was less than $0.1 million for the year ended December 31, 2014. These results have been recorded in discontinued operations under “Loss from discontinued operations, net of income tax benefit.” No interest expense has been allocated to discontinued operations.

Revenue and pre‑tax income (loss) related to discontinued operations are as follows (in thousands):


	Year Ended December 31,
	2016		2015		2014
Revenue		—		—	$	7
Pre-tax loss		—		—	$	(25)

- Definition

The entire disclosure related to a disposal group. Includes, but is not limited to, a discontinued operation, disposal classified as held-for-sale or disposed of by means other than sale or disposal of an individually significant component.

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+ Details

Goodwill and Identifiable Intangible Assets, Net

12 Months Ended

Dec. 31, 2016

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):


	December 31,
	2016		2015
Balance at beginning of year	$	143,874	$	140,341
Additions (See Note 4)		5,334		3,533
Balance at end of year	$	149,208	$	143,874

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, 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, 2016. Based on this assessment, we concluded that the fair value of each of the reporting units was greater than its carrying value.

During 2015 and 2014, we performed a qualitative assessment for each reporting unit, 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.

Prior to our annual goodwill impairment test in 2014, we recorded a goodwill impairment charge of $0.7 million during the second quarter of 2014. Based on market activity declines and write-downs incurred on several jobs, we determined that the operating environment, conditions and performance at our operating unit based in California could no longer support the related goodwill balance. When the carrying value of a given reporting unit exceeds its fair value, an impairment loss is recorded to the extent that the implied fair value of the goodwill of the reporting unit is less than its carrying value. The fair value was estimated using a discounted cash flow model combined with market valuation approaches.

As of October 1, 2016, the fair value exceeded the carrying value by a significant margin for all of our reporting units with a goodwill balance.

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):


	Estimated	2016				2015
	Useful Lives	Gross Book		Accumulated		Gross Book		Accumulated
	in Years	Value		Amortization		Value		Amortization
Customer relationships	1 - 15	$	57,230	$	(36,758)	$	53,334	$	(31,960)
Backlog	1 - 2		3,600		(3,433)		1,600		(1,412)
Noncompete agreements	2 - 7		2,890		(2,890)		2,890		(2,890)
Tradenames	2 - 25		31,640		(9,844)		27,995		(8,478)
Total		$	95,360	$	(52,925)	$	85,819	$	(44,740)

The amounts attributable to customer relationships, noncompete agreements and tradenames are amortized to “Selling, General and Administrative Expenses” on a pattern of economic benefit or a straight‑line method over periods from two to twenty‑five years. 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, 2016, 2015 and 2014 was $8.2 million, $7.5 million and $7.7 million, respectively.

At December 31, 2016, future amortization expense of identifiable intangible assets is as follows (in thousands):


Year ended December 31—
2017	$	5,702
2018		4,861
2019		4,246
2020		3,751
2021		3,300
Thereafter		20,575
Total	$	42,435

- Definition

The entire disclosure for the aggregate amount of goodwill and a description of intangible assets, which may include (a) for amortizable intangible assets (also referred to as finite-lived intangible assets), the carrying amount, the amount of any significant residual value, and the weighted-average amortization period, (b) for intangible assets not subject to amortization (also referred to as indefinite-lived intangible assets), the carrying amount, and (c) the amount of research and development assets acquired and written off in the period, including the line item in the income statement in which the amounts written off are aggregated, if not readily apparent from the income statement. Also discloses (a) for amortizable intangibles assets in total and by major class, the gross carrying amount and accumulated amortization, the total amortization expense for the period, and the estimated aggregate amortization expense for each of the five succeeding fiscal years, (b) for intangible assets not subject to amortization the carrying amount in total and by major class, and (c) for goodwill, in total and for each reportable segment, the changes in the carrying amount of goodwill during the period (including the aggregate amount of goodwill acquired, the aggregate amount of impairment losses recognized, and the amount of goodwill included in the gain (loss) on disposal of a reporting unit). If any part of goodwill has not been allocated to a reportable segment, discloses the unallocated amount and the reasons for not allocating. For each impairment loss recognized related to an intangible asset (excluding goodwill), discloses: (a) a description of the impaired intangible asset and the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method for determining fair value, (c) the caption in the income statement or the statement of activities in which the impairment loss is aggregated, and (d) the segment in which the impaired intangible asset is reported. For each goodwill impairment loss recognized, discloses: (a) a description of the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method of determining the fair value of the associated reporting unit, and (c) if a recognized impairment loss is an estimate not finalized and the reasons why the estimate is not final. May also disclose the nature and amount of any significant adjustments made to a previous estimate of an impairment loss.

+ References + Details

Property and Equipment

12 Months Ended

Dec. 31, 2016

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	2016		2015
Land	—	$	2,745	$	2,745
Transportation equipment	1 - 7		74,137		64,951
Machinery and equipment	1 - 20		27,843		25,118
Computer and telephone equipment	1 - 10		20,791		21,141
Buildings and leasehold improvements	1 - 40		35,166		30,319
Furniture and fixtures	1 - 17		4,224		4,181
Construction in progress	—		425		—
			165,331		148,455
Less—Accumulated depreciation			(97,136)		(87,642)
Property and equipment, net		$	68,195	$	60,813

Depreciation expense, including capital lease amortization, for the years ended December 31, 2016, 2015 and 2014 was $18.0 million, $15.9 million and $13.7 million, respectively.

Detail of Certain Balance Sheet Accounts

12 Months Ended

Dec. 31, 2016

Detail of Certain Balance Sheet Accounts

Detail of Certain Balance Sheet Accounts

8. Detail of Certain Balance Sheet Accounts

Activity in our allowance for doubtful accounts consists of the following (in thousands):


	December 31,
	2016		2015		2014
Balance at beginning of year	$	5,158	$	4,379	$	4,460
Bad debt expense (benefit)		(27)		1,552		1,275
Deductions for uncollectible receivables written off, net of recoveries		(876)		(798)		(1,650)
Allowance for doubtful accounts of acquired companies at date of acquisition		33		25		294
Balance at end of year	$	4,288	$	5,158	$	4,379

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


	December 31,
	2016		2015
Accrued warranty costs	$	6,702	$	7,746
Accrued job losses		1,269		1,365
Accrued sales and use tax		1,973		2,216
Deferred revenue		5,257		2,175
Liabilities due to former owners		4,196		2,650
Other current liabilities		14,864		12,525
	$	34,261	$	28,677

Long-Term Debt Obligations

12 Months Ended

Dec. 31, 2016

Debt Obligations

Debt Obligations

9. Long‑Term Debt Obligations

Long‑term debt obligations consist of the following (in thousands):


	December 31,
	2016		2015
Revolving credit facility	$	—	$	10,000
Notes to former owners		2,250		1,000
Other debt		305		—
Capital lease obligations		256		507
Total debt		2,811		11,507
Less—current portion		(763)		(751)
Total long-term portion of debt	$	2,048	$	10,756

At December 31, 2016, future principal payments of debt are as follows (in thousands):


Year ended December 31—
2017	$	763
2018		1,046
2019		1,002
2020		—
2021		—
Thereafter		—
	$	2,811

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


	Year Ended December 31,
	2016		2015		2014
Interest expense on notes to former owners	$	70	$	25	$	38
Interest expense on borrowings and unused commitment fees		1,251		692		790
Letter of credit fees		657		719		747
Amortization of debt financing costs		367		317		283
Total	$	2,345	$	1,753	$	1,858

Revolving Credit Facility

On February 22, 2016, we amended our senior credit facility (the “Facility”) provided by a syndicate of banks, increasing our borrowing capacity from $250.0 million to $325.0 million, with a $100 million accordion option. The Facility, which is available for borrowings and letters of credit, expires in February 2021 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 a second lien on our assets related to projects subject to surety bonds. In 2016, we incurred approximately $0.8 million in financing and professional costs in connection with an amendment to the Facility, which combined with the previous unamortized costs of $1.1 million, are being amortized on a straight‑line basis as a non‑cash charge to interest expense over the remaining term of the Facility. As of December 31, 2016, we had no outstanding borrowings, $41.5 million in letters of credit outstanding and $283.5 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, 2016, the book value of these assets was approximately $41.5 million.

Covenants and Restrictions

The Facility contains financial covenants defining various 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) 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 2016 (in thousands):


Net income including noncontrolling interests	$	64,896
Income tax expense		36,165
Interest expense, net		2,336
Depreciation and amortization expense		26,166
Stock-based compensation		5,041
Pre-acquisition results of acquired companies, as defined under the Facility		10
Credit Facility Adjusted EBITDA	$	134,614

The Facility’s principal financial covenants include:

Leverage Ratio—The Facility requires that the ratio of our Consolidated Total Indebtedness to our Credit Facility Adjusted EBITDA not exceed (i) 3.00 to 1.00 as of the end of each fiscal quarter through September 30, 2017, and (ii) 2.75 to 1.00 as of the end of each fiscal quarter thereafter through maturity. The leverage ratio as of December 31, 2016 was 0.02.

Fixed Charge Coverage Ratio—The Facility requires that the ratio of Credit Facility Adjusted EBITDA, less non-financed capital expenditures, tax provision, dividends and amounts used to repurchase stock to the sum of interest expense and scheduled principal payments of indebtedness be at least 2.00 to 1.00; provided that the calculation of the fixed charge coverage ratio excludes stock repurchases and the payment of dividends at any time that the Company’s Net Leverage Ratio does not exceed 1.50 to 1.00. The Facility also allows the fixed charge coverage ratio not to be reduced for stock repurchases through September 30, 2015 in an aggregate amount not to exceed $25 million and for stock repurchases made after February 22, 2016 but on or prior to December 31, 2017 in an aggregate amount not to exceed $25 million, if at the time of and after giving effect to such repurchase the Company’s Net Leverage Ratio was less than or equal to 1.50 to 1.00. Capital expenditures, tax provision, dividends and stock repurchase 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, 2016 was 27.84.

Other Restrictions—The Facility permits acquisitions of up to $30.0 million per transaction, provided that the aggregate purchase price of such an acquisition and of acquisitions in the same fiscal year does not exceed $65.0 million. However, these limitations only apply when the Company’s Net Leverage Ratio is equal to or greater than 2.00 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, 2016.

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. 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” for the twelve months ending as of that quarter end, as defined in the credit agreement and shown below.

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, 2016 relating to interest options under the Facility:


Base Rate Loan Option:
Federal Funds Rate plus 0.50%		1.16%
Wells Fargo Bank, N.A. Prime Rate		3.75%
One-month LIBOR plus 1.00%		1.77%
Eurodollar Rate Loan Option:
One-month LIBOR		0.77%
Six-month LIBOR		1.32%

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, as defined in the credit agreement.


	Consolidated Total Indebtedness to
	Credit Facility Adjusted EBITDA
	Less than 0.75		0.75 to 1.50		1.50 to 2.25		2.25 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	%

We estimate that the weighted average interest rate applicable to the borrowings under the Facility would be approximately 1.8% as of December 31, 2016.

Notes to Former Owners

As part of the consideration used to acquire two companies, we have outstanding subordinated notes to the former owners. These notes had an outstanding balance of $2.3 million as of December 31, 2016. In conjunction with the Shoffner acquisition in the first quarter, we issued a subordinated note to former owners with an outstanding balance of $1.8 million as of December 31, 2016 that bears interest, payable quarterly, at a weighted average interest rate of 3.0%. The principal is due in equal installments in February 2018 and 2019. In conjunction with an immaterial acquisition in the fourth quarter of 2014, we issued a subordinated note to the former owners of the acquired company as part of the consideration used to acquire the company. This note had an outstanding balance of $0.5 million as of December 31, 2016 and bears interest, payable quarterly, at a weighted average interest rate of 2.5%. The principal is due in October 2017.

Other Debt

As part of the Shoffner acquisition, we acquired debt with an outstanding balance at the acquisition date of $0.4 million with principle and interest due the last day of every month; ending on the December 30, 2019 maturity date. The interest rate is the one month LIBOR rate plus 2.25%. As of December 31, 2016, $0.3 million of the note was outstanding, of which $0.1 million was considered current.

In conjunction with one of our acquisitions, we acquired capital lease obligations. As of December 31, 2016, $0.3 million of capital lease obligations were outstanding, of which $0.2 million was considered current.

Income Taxes

12 Months Ended

Dec. 31, 2016

Income Taxes

Income Taxes

10. Income Taxes

Provision for Income Taxes

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


	December 31,
	2016		2015		2014
Current—
Federal	$	32,721	$	27,564	$	13,402
State and Puerto Rico		4,683		4,065		2,810
		37,404		31,629		16,212
Deferred—
Federal		(2,101)		(1,481)		(308)
State and Puerto Rico		862		1,076		(4,290)
		(1,239)		(405)		(4,598)
	$	36,165	$	31,224	$	11,614

The difference in income taxes provided for and the amounts determined by applying the federal statutory tax rate to income before income taxes results from the following (in thousands):


	December 31,
	2016		2015		2014
Income tax expense at the statutory rate of 35%	$	35,371	$	31,032	$	14,080
Changes resulting from—
State income taxes, net of federal tax effect		4,262		3,432		1,653
Increase (decrease) in valuation allowance		(1,254)		463		(1,944)
Increase (decrease) in tax contingency reserves		20		(72)		(40)
Increase (decrease) from noncontrolling interests		—		(2,827)		(1,938)
Non-deductible expenses		825		751		704
Equity based stock compensation deduction		(885)		—		—
Production activity deduction		(2,026)		(1,701)		(694)
Purchase accounting adjustments		—		—		(46)
Other		(148)		146		(161)
	$	36,165	$	31,224	$	11,614

Deferred Tax Assets (Liabilities)

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


	Year Ended
	December 31,
	2016		2015
Deferred income tax assets—
Accounts receivable and allowance for doubtful accounts	$	1,627	$	1,889
Stock compensation		3,036		3,080
Accrued liabilities and expenses		23,000		19,174
State net operating loss carryforwards		5,053		6,781
Goodwill		875		—
Other		759		830
Total deferred income tax assets		34,350		31,754
Deferred income tax liabilities—
Property and equipment		(4,398)		(5,572)
Long-term contracts		(637)		(728)
Goodwill		—		(6,037)
Intangible assets		(737)		(156)
Other		(513)		(357)
Total deferred income tax liabilities		(6,285)		(12,850)
Less—Valuation allowance		(3,184)		(4,438)
Net deferred income tax assets	$	24,881	$	14,466

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


	December 31,
	2016		2015
Deferred income tax assets	$	27,170	$	16,276
Deferred income tax liabilities	$	2,289	$	1,810

As of December 31, 2016, we had $5.1 million of future tax benefits related to $70.4 million of available federal, state and Puerto Rican net operating loss carryforwards (“NOLs”), which expire between 2017 and 2036. A valuation allowance of $3.2 million has been recorded against certain state and Puerto Rican net deferred tax assets. We recorded a decrease in valuation allowances of $1.3 million for the year ended December 31, 2016. Our deferred tax assets for Puerto Rico are fully valued. A deferred tax asset for state NOLs, net of related valuation allowance, of $2.2 million reflects our conclusion that it is likely that this asset will be realized based upon expected future earnings in certain subsidiaries. We update this assessment of the realizability of deferred tax assets relating to state net NOLs annually. A return to profitability in our entities with valuation allowances on their NOL’s and deferred tax assets would result in a reversal of a portion of the valuation allowance relating to realized deferred tax assets. A sustained period of profitability could cause a change in our judgment of the remaining deferred tax assets. If that were to occur then it is likely that we would reverse some or all of the remaining deferred tax asset valuation allowance.

As of December 31, 2016 and 2015, approximately $0.2 million of unrecognized tax benefits, if recognized in future periods, would impact our effective tax rate. This liability is included in “Other Long‑Term Liabilities” in the consolidated balance sheets. We do not expect that the total amount of unrecognized tax benefits will significantly increase or decrease within the next twelve months.

We recognize potential interest and penalties related to unrecognized tax benefits in income tax expense. We had accrued approximately $0.4 million and $0.3 million for the payment of interest and penalties at December 31, 2016 and 2015, respectively. Our tax records are subject to review by the Internal Revenue Service for the 2013 tax year forward and by various state authorities for the 2008 tax year forward.

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,
	2016		2015		2014
Balance at beginning of year	$	240	$	343	$	413
Additions based on tax positions related to the current year		—		—		—
Additions for tax positions of prior years		—		—		—
Reductions for tax positions of prior years		—		(103)		(70)
Settlements		—		—		—
Balance at end of year	$	240	$	240	$	343

Employee Benefit Plans	12 Months Ended
Employee Benefit Plans	Dec. 31, 2016
Employee Benefit Plans
Employee Benefit Plans	11. 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 $7.8 million in 2016, $7.1 million in 2015 and $6.1 million in 2014. Of these amounts, approximately $0.2 million and $0.1 million was payable to the plans at December 31, 2016 and 2015, 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, 2016 and 2015, we had 5 and 11 employees, respectively, who were union members. There were no contributions made to multi‑employer pension plans in 2016, 2015 or 2014. 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 $3.3 million recorded as of December 31, 2016 and 2015, respectively.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2016

Commitments and Contingencies

Commitments and Contingencies

12. Commitments and Contingencies

Leases

We lease certain facilities and equipment under noncancelable operating leases. Rent expense for the years ended December 31, 2016, 2015 and 2014 was $20.6 million, $20.6 million, and $17.8 million, respectively. We recognize escalating rental payments that are quantifiable at the inception of the lease on a straight‑line basis over the lease term. Concurrent with the acquisitions of certain companies, we entered into various agreements with previous owners to lease buildings used in our operations. The terms of these leases generally range from three to ten years and certain leases provide for escalations in the rental expenses each year, the majority of which are based on inflation. Included in the 2016, 2015 and 2014 rent expense above are approximately $5.1 million, $5.4 million and $3.8 million of rent paid to these related parties, respectively. In addition to the noncancelable operating leases, we have capital lease obligations of $0.3 million as of December 31, 2016, which were attained through our acquisition in Northern Texas.

The following represents future minimum rental payments under noncancelable operating leases (in thousands):


Year ended December 31—
2017	$	13,098
2018		11,904
2019		9,666
2020		7,204
2021		5,051
Thereafter		9,107
	$	56,030

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.

In the fourth quarter of 2016, we entered into a settlement agreement with British Petroleum (“BP”) related to a claim from one of our subsidiaries regarding the April 2010 BP Deepwater Horizon oil spill. We recorded a $0.6 million gain in the fourth quarter of 2016 in Other Income as a result of this settlement. While we still have other subsidiaries with outstanding claims against BP related to this matter, we cannot predict when or if we will receive any further settlement compensation as a result of these outstanding claims.

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.

Surety market conditions are favorable and bonding capacity is adequate in the current market conditions along with acceptable terms and conditions. Historically, approximately 20% to 30% 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, 2016 were as follows:

Workers’ Compensation—The per‑incident deductible for workers’ compensation is $1.0 million. Losses above $1.0 million 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 $1.0 million and then we have several layers of excess loss insurance policies that cover losses up to $100.0 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 $1.0 million. We are fully insured for the next $1.0 million of each loss, and then have several layers of excess loss insurance policies that cover losses up to $100.0 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 $0.5 million. We are fully insured for the next $1.5 million of each loss, and then have several layers of excess loss insurance policies that cover losses up to $100.0 million in aggregate across this risk area (as well as employer’s liability and general liability noted above).

Employee Medical—We have two 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 $100.0 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 $100.0 million of excess loss coverage for each of general liability, employer’s liability and auto liability.

Stockholders' Equity

12 Months Ended

Dec. 31, 2016

Stockholders' Equity

Stockholders' Equity

13. 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, 2016, there were 3.2 million shares available for issuance under this plan. The 2012 Plan will expire in May 2022. 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 (the “Board”) 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 approved extensions of the program to acquire additional shares. On August 11, 2016, the Board approved an extension to the program by increasing the shares authorized for repurchase by 0.6 million shares. Since the inception of the repurchase program, the Board has approved 8.1 million shares to be repurchased. As of December 31, 2016, we have repurchased a cumulative total of 7.3 million shares at an average price of $13.02 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, 2016, we repurchased 0.5 million shares for approximately $13.1 million at an average price of $28.44 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 approximately 0.1 million anti-dilutive stock options excluded from the calculation of diluted EPS for the year ended December 31, 2016. There were no anti-dilutive stock options for the year ended December 31, 2015. There were approximately 0.2 million anti-dilutive stock options excluded from the calculation of diluted EPS for the year ended December 31, 2014.

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,
	2016	2015	2014
Common shares outstanding, end of period	37,209	37,427	37,270
Effect of using weighted average common shares outstanding	126	15	277
Shares used in computing earnings per share—basic	37,335	37,442	37,547
Effect of shares issuable under stock option plans based on the treasury stock method	330	266	147
Effect of restricted and contingently issuable shares	146	160	103
Shares used in computing earnings per share—diluted	37,811	37,868	37,797

Stock-Based Compensation

12 Months Ended

Dec. 31, 2016

Stock-Based Compensation

Stock-Based Compensation

14. Stock‑Based Compensation

Under the 2012 Equity Incentive Plan (the “2012 Plan”) grants of stock options, restricted stock and restricted stock units, and performance share units have been, and will be, determined and administered by the compensation committee of the Board of Directors. Total stock‑based compensation expense was $5.0 million, $5.6 million and $4.8 million for the years ended December 31, 2016, 2015 and 2014, 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 $1.9 million, $2.1 million and $1.8 million for each of the years ended December 31, 2016, 2015 and 2014. Subsequent to our adoption of ASU 2016-09 in the second quarter of 2016, we elected to apply the presentation requirements for cash flows related to excess tax benefits prospectively. As such, we present, in the consolidated statements of cash flows, the benefits of tax deductions in excess of recognized compensation costs (“excess tax benefits”) as operating cash flows for the year ended 2016 and as financing cash flows for the years ended 2015 and 2014.

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,
	2016
		Weighted-
		Average
Stock Options	Shares	Exercise Price
Outstanding at beginning of year	724	$	14.69
Granted	102	$	30.36
Exercised	(112)	$	14.11
Forfeited	—	$	—
Expired	—	$	—
Outstanding at end of year	714	$	17.01
Options exercisable at end of year	473

The total intrinsic value of options exercised during the years ended December 31, 2016, 2015 and 2014 was $1.9 million, $3.9 million and $0.4 million, respectively. Stock options exercisable as of December 31, 2016 have a weighted‑average remaining contractual term of 5.3 years and an aggregate intrinsic value of $9.2 million. As of December 31, 2016, we have 0.7 million options that are vested or expected to vest; these options have a weighted average exercise price of $17.01 per share, have a weighted‑average remaining contractual term of 6.4 years and an aggregate intrinsic value of $11.6 million.

The following table summarizes information about stock options outstanding at December 31, 2016 (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	12/31/2016	Life	Exercise Price		12/31/2016	Exercise Price
$11.00 - $15.00	361	4.63	$	12.64	361	$	12.64
$15.01 - $20.00	251	7.72	$	17.89	112	$	17.30
$20.01 - $30.36	102	9.23	$	30.36	—	$	—
$11.00 - $30.36	714	6.37	$	17.01	473	$	13.74

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. The fair values and the assumptions used for the 2016, 2015 and 2014 grants are shown in the table below:


	Year Ended December 31,
	2016		2015		2014
Weighted-average fair value per share of options granted	$	9.94	$	6.33	$	6.24
Fair value assumptions:
Expected dividend yield		0.97%		1.51%		1.34%
Expected stock price volatility		37.9%		38.4%		45.2%
Risk-free interest rate		1.41%		1.50%		1.91%
Expected term		5.3 years		5.6 years		5.6 years

Stock options are accounted for as equity instruments. As of December 31, 2016, the unrecognized compensation cost related to stock options was $0.8 million, which is expected to be recognized over a weighted‑average period of 1.5 years. The total fair value of options vested during the year ended December 31, 2016 was $0.9 million.

The following table summarizes information about nonvested stock option awards as of December 31, 2016 and changes for the year ended December 31, 2016 (shares in thousands):


		Weighted-Average
		Grant Date
Stock Options	Shares	Fair Value
Nonvested at December 31, 2015	287	$	6.07
Granted	102	$	9.94
Vested	(148)	$	5.85
Forfeited	—		—
Nonvested at December 31, 2016	241	$	7.83

Restricted Stock and Restricted Stock Units

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


	Year Ended
	December 31,
	2016
		Weighted
		Average Grant
Restricted Stock and Restricted Stock Units	Shares	Date Fair Value
Unvested at beginning of year	149	$	17.48
Granted	85	$	30.25
Vested	(108)	$	20.61
Forfeited	—	$	—
Unvested at end of year	126	$	23.41

Approximately $1.3 million of compensation expense related to restricted stock and restricted stock units will be recognized over a weighted‑average period of 1.6 years. The total fair value of shares vested during the year ended December 31, 2016 was $2.2 million. The weighted‑average fair value per share of restricted stock shares and units awarded during 2016, 2015 and 2014 was $30.25, $20.64 and $15.80, respectively. The aggregate intrinsic value of restricted stock vested during the years ended December 31, 2016, 2015 and 2014 was $3.6 million, $3.4 million and $2.9 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 an accrued 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, 2016 was $4.8 million. Of this amount, $1.8 million relates to the PSUs granted in 2014 whose performance period ended December 31, 2016. 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, 2016, 2015 and 2014 was $1.6 million, $2.6 million and $1.8 million, respectively. At the December 31, 2016 calculated fair market value, approximately $1.5 million of compensation expense related to performance stock units will be recognized over a weighted‑average period of 1.1 years.

- Definition

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.

+ References + Details

Selected Quarterly Financial Data (Unaudited)

12 Months Ended

Dec. 31, 2016

Selected Quarterly Financial Data (Unaudited)

Selected Quarterly Financial Data (Unaudited)

15. Selected Quarterly Financial Data (Unaudited)

Quarterly financial information for the years ended December 31, 2016 and 2015 is summarized as follows (in thousands, except per share data):


	2016
	Q1		Q2		Q3		Q4
Revenue	$	385,942	$	427,538	$	428,760	$	392,100
Gross profit		73,502		89,426		92,816		88,265
Net income including noncontrolling interests		9,841		17,717		20,471		16,867
Net income attributable to Comfort Systems USA, Inc.		9,841		17,717		20,471		16,867
INCOME PER SHARE ATTRIBUTABLE TO COMFORT SYSTEMS USA, INC.:
Basic—
Income from continuing operations	$	0.26	$	0.47	$	0.55	$	0.45
Income from discontinued operations		—		—		—		—
Net income	$	0.26	$	0.47	$	0.55	$	0.45
Diluted—
Income from continuing operations	$	0.26	$	0.47	$	0.54	$	0.45
Income from discontinued operations		—		—		—		—
Net income	$	0.26	$	0.47	$	0.54	$	0.45


	2015
	Q1		Q2		Q3		Q4
Revenue	$	369,547	$	416,567	$	410,565	$	383,840
Gross profit (1)		64,688		82,049		87,465		83,927
Net income including noncontrolling interests		6,889		15,782		19,886		14,883
Net income attributable to Comfort Systems USA, Inc.		5,066		13,404		17,673		13,221
INCOME PER SHARE ATTRIBUTABLE TO COMFORT SYSTEMS USA, INC.:
Basic—
Income from continuing operations	$	0.14	$	0.36	$	0.47	$	0.35
Income from discontinued operations		—		—		—		—
Net income	$	0.14	$	0.36	$	0.47	$	0.35
Diluted—
Income from continuing operations	$	0.13	$	0.35	$	0.46	$	0.35
Income from discontinued operations		—		—		—		—
Net income	$	0.13	$	0.35	$	0.46	$	0.35

(1)

In the fourth quarter of 2015, we recognized a $3.4 million project gain related to change orders we received.

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.

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2016
Subsequent Events.
Subsequent Events	16. Subsequent Events On February 21, 2017, we entered into a definitive purchase agreement to acquire all of the issued and outstanding stock of BCH Holdings, Inc. and each of its wholly-owned subsidiaries (collectively “BCH”) for $100 million, comprised of $85.7 million in cash at closing and $14.3 million in a promissory note that is payable in two equal installments of $7.15 million on the third and fourth anniversaries of the closing date, plus an earn‑out that we will pay if certain financial targets are met after the acquisition date as well as a customary working capital adjustment. BCH is an integrated, single-source provider of mechanical service, maintenance and construction with headquarters in Tampa, Florida and operations throughout the southeastern region of the United States. We currently expect this transaction to close around the beginning of the second quarter of 2017.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2016

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,
	2016		2015		2014
Interest	$	1,864	$	1,408	$	1,764
Income taxes	$	29,349	$	35,538	$	15,366

Recent Accounting Pronouncements

Revenue Recognition

Contracts in progress are as follows (in thousands):


	December 31,
	2016		2015
Costs incurred on contracts in progress	$	1,116,182	$	1,135,279
Estimated earnings, net of losses		207,252		188,243
Less—Billings to date		(1,378,050)		(1,377,581)
	$	(54,616)	$	(54,059)
Costs and estimated earnings in excess of billings	$	29,369	$	31,338
Billings in excess of costs and estimated earnings		(83,985)		(85,397)
	$	(54,616)	$	(54,059)

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.

Accounts Receivable

Inventories

Property and Equipment

Recoverability of Goodwill and Identifiable Intangible Assets

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.

Long-Lived 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

Self‑Insurance Liabilities

Warranty Costs

Income Taxes

Segment Disclosure

Concentrations of Credit Risk

Financial Instruments

Business and Organization (Tables)

12 Months Ended

Dec. 31, 2016

Business and Organization

Schedule of service activities


	Revenue
Service Activity	$ in thousands		%
HVAC	$	1,225,755	75	%
Plumbing		245,151	15	%
Building Automation Control Systems		98,060	6	%
Other		65,374	4	%
Total	$	1,634,340	100	%

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2016

Summary of Significant Accounting Policies

Schedule of cash paid

Cash paid (in thousands) for:


	Year Ended December 31,
	2016		2015		2014
Interest	$	1,864	$	1,408	$	1,764
Income taxes	$	29,349	$	35,538	$	15,366

Schedule of contracts in progress

Contracts in progress are as follows (in thousands):


	December 31,
	2016		2015
Costs incurred on contracts in progress	$	1,116,182	$	1,135,279
Estimated earnings, net of losses		207,252		188,243
Less—Billings to date		(1,378,050)		(1,377,581)
	$	(54,616)	$	(54,059)
Costs and estimated earnings in excess of billings	$	29,369	$	31,338
Billings in excess of costs and estimated earnings		(83,985)		(85,397)
	$	(54,616)	$	(54,059)

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2016

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



	Balance		Fair Value Measurements at Reporting Date
	December 31,
	2016		Level 1		Level 2		Level 3
Cash and cash equivalents	$	32,074	$	32,074	$	—	$	—
Life insurance—cash surrender value	$	3,697	$	—	$	3,697	$	—
Contingent earn-out obligations	$	2,531	$	—	$	—	$	2,531

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).


Balance at beginning of year	$	450
Issuances		3,240
Settlements		(428)
Adjustments to fair value		(731)
Balance at December 31, 2016	$	2,531

Discontinued Operations (Tables)

12 Months Ended

Dec. 31, 2016

Discontinued Operations

Schedule of revenue and pre-tax income (loss) related to discontinued operations

Revenue and pre‑tax income (loss) related to discontinued operations are as follows (in thousands):


	Year Ended December 31,
	2016		2015		2014
Revenue		—		—	$	7
Pre-tax loss		—		—	$	(25)

- Definition

Tabular disclosure of information related to a disposal group. Includes, but is not limited to, a discontinued operation, disposal classified as held-for-sale or disposed of by means other than sale or disposal of an individually significant component.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=65878427&loc=SL51721533-107759

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 4B
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721665-107760

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=64827811&loc=d3e1474-107760

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=64827811&loc=d3e1361-107760

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721683-107760

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 3A
-URI http://asc.fasb.org/extlink&oid=64862545&loc=SL51724579-110230

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 5C
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721675-107760

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 4A
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721663-107760

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=64862545&loc=d3e2941-110230

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 5B
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721673-107760

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 3A
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721659-107760

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 5A
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721671-107760

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 5D
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721677-107760

+ Details

Goodwill and Identifiable Intangible Assets, Net (Tables)

12 Months Ended

Dec. 31, 2016

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):


	December 31,
	2016		2015
Balance at beginning of year	$	143,874	$	140,341
Additions (See Note 4)		5,334		3,533
Balance at end of year	$	149,208	$	143,874

Schedule of components of identifiable intangible assets

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


	Estimated	2016				2015
	Useful Lives	Gross Book		Accumulated		Gross Book		Accumulated
	in Years	Value		Amortization		Value		Amortization
Customer relationships	1 - 15	$	57,230	$	(36,758)	$	53,334	$	(31,960)
Backlog	1 - 2		3,600		(3,433)		1,600		(1,412)
Noncompete agreements	2 - 7		2,890		(2,890)		2,890		(2,890)
Tradenames	2 - 25		31,640		(9,844)		27,995		(8,478)
Total		$	95,360	$	(52,925)	$	85,819	$	(44,740)

Schedule of future amortization expense of identifiable intangible assets

At December 31, 2016, future amortization expense of identifiable intangible assets is as follows (in thousands):


Year ended December 31—
2017	$	5,702
2018		4,861
2019		4,246
2020		3,751
2021		3,300
Thereafter		20,575
Total	$	42,435

Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2016

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	2016		2015
Land	—	$	2,745	$	2,745
Transportation equipment	1 - 7		74,137		64,951
Machinery and equipment	1 - 20		27,843		25,118
Computer and telephone equipment	1 - 10		20,791		21,141
Buildings and leasehold improvements	1 - 40		35,166		30,319
Furniture and fixtures	1 - 17		4,224		4,181
Construction in progress	—		425		—
			165,331		148,455
Less—Accumulated depreciation			(97,136)		(87,642)
Property and equipment, net		$	68,195	$	60,813

Detail of Certain Balance Sheet Accounts (Tables)

12 Months Ended

Dec. 31, 2016

Detail of Certain Balance Sheet Accounts

Schedule of activity in allowance for doubtful accounts

Activity in our allowance for doubtful accounts consists of the following (in thousands):


	December 31,
	2016		2015		2014
Balance at beginning of year	$	5,158	$	4,379	$	4,460
Bad debt expense (benefit)		(27)		1,552		1,275
Deductions for uncollectible receivables written off, net of recoveries		(876)		(798)		(1,650)
Allowance for doubtful accounts of acquired companies at date of acquisition		33		25		294
Balance at end of year	$	4,288	$	5,158	$	4,379

Schedule of other current liabilities

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


	December 31,
	2016		2015
Accrued warranty costs	$	6,702	$	7,746
Accrued job losses		1,269		1,365
Accrued sales and use tax		1,973		2,216
Deferred revenue		5,257		2,175
Liabilities due to former owners		4,196		2,650
Other current liabilities		14,864		12,525
	$	34,261	$	28,677

Long-Term Debt Obligations (Tables)

12 Months Ended

Dec. 31, 2016

Debt Obligations

Schedule of components of debt obligations

Long‑term debt obligations consist of the following (in thousands):


	December 31,
	2016		2015
Revolving credit facility	$	—	$	10,000
Notes to former owners		2,250		1,000
Other debt		305		—
Capital lease obligations		256		507
Total debt		2,811		11,507
Less—current portion		(763)		(751)
Total long-term portion of debt	$	2,048	$	10,756

Schedule of future principal payments of long-term debt

At December 31, 2016, future principal payments of debt are as follows (in thousands):


Year ended December 31—
2017	$	763
2018		1,046
2019		1,002
2020		—
2021		—
Thereafter		—
	$	2,811

Schedule of interest expense

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


	Year Ended December 31,
	2016		2015		2014
Interest expense on notes to former owners	$	70	$	25	$	38
Interest expense on borrowings and unused commitment fees		1,251		692		790
Letter of credit fees		657		719		747
Amortization of debt financing costs		367		317		283
Total	$	2,345	$	1,753	$	1,858

Schedule of reconciliation of Credit Facility Adjusted EBITDA to net income

The following is a reconciliation of Credit Facility Adjusted EBITDA to net income for 2016 (in thousands):


Net income including noncontrolling interests	$	64,896
Income tax expense		36,165
Interest expense, net		2,336
Depreciation and amortization expense		26,166
Stock-based compensation		5,041
Pre-acquisition results of acquired companies, as defined under the Facility		10
Credit Facility Adjusted EBITDA	$	134,614

Schedule of market rates relating to interest options under the Facility

the following are the respective market rates as of December 31, 2016 relating to interest options under the Facility:


Base Rate Loan Option:
Federal Funds Rate plus 0.50%		1.16%
Wells Fargo Bank, N.A. Prime Rate		3.75%
One-month LIBOR plus 1.00%		1.77%
Eurodollar Rate Loan Option:
One-month LIBOR		0.77%
Six-month LIBOR		1.32%

Summary of additional margins


	Consolidated Total Indebtedness to
	Credit Facility Adjusted EBITDA
	Less than 0.75		0.75 to 1.50		1.50 to 2.25		2.25 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	%

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2016

Income Taxes

Schedule of provision for income taxes relating to continuing operations

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


	December 31,
	2016		2015		2014
Current—
Federal	$	32,721	$	27,564	$	13,402
State and Puerto Rico		4,683		4,065		2,810
		37,404		31,629		16,212
Deferred—
Federal		(2,101)		(1,481)		(308)
State and Puerto Rico		862		1,076		(4,290)
		(1,239)		(405)		(4,598)
	$	36,165	$	31,224	$	11,614

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

The difference in income taxes provided for and the amounts determined by applying the federal statutory tax rate to income before income taxes results from the following (in thousands):


	December 31,
	2016		2015		2014
Income tax expense at the statutory rate of 35%	$	35,371	$	31,032	$	14,080
Changes resulting from—
State income taxes, net of federal tax effect		4,262		3,432		1,653
Increase (decrease) in valuation allowance		(1,254)		463		(1,944)
Increase (decrease) in tax contingency reserves		20		(72)		(40)
Increase (decrease) from noncontrolling interests		—		(2,827)		(1,938)
Non-deductible expenses		825		751		704
Equity based stock compensation deduction		(885)		—		—
Production activity deduction		(2,026)		(1,701)		(694)
Purchase accounting adjustments		—		—		(46)
Other		(148)		146		(161)
	$	36,165	$	31,224	$	11,614

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 net deferred tax assets and net deferred tax liabilities as reflected on the balance sheet are as follows (in thousands):


	Year Ended
	December 31,
	2016		2015
Deferred income tax assets—
Accounts receivable and allowance for doubtful accounts	$	1,627	$	1,889
Stock compensation		3,036		3,080
Accrued liabilities and expenses		23,000		19,174
State net operating loss carryforwards		5,053		6,781
Goodwill		875		—
Other		759		830
Total deferred income tax assets		34,350		31,754
Deferred income tax liabilities—
Property and equipment		(4,398)		(5,572)
Long-term contracts		(637)		(728)
Goodwill		—		(6,037)
Intangible assets		(737)		(156)
Other		(513)		(357)
Total deferred income tax liabilities		(6,285)		(12,850)
Less—Valuation allowance		(3,184)		(4,438)
Net deferred income tax assets	$	24,881	$	14,466

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

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


	December 31,
	2016		2015
Deferred income tax assets	$	27,170	$	16,276
Deferred income tax liabilities	$	2,289	$	1,810

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,
	2016		2015		2014
Balance at beginning of year	$	240	$	343	$	413
Additions based on tax positions related to the current year		—		—		—
Additions for tax positions of prior years		—		—		—
Reductions for tax positions of prior years		—		(103)		(70)
Settlements		—		—		—
Balance at end of year	$	240	$	240	$	343

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2016

Commitments and Contingencies

Schedule of future minimum rental payments under noncancelable operating leases

The following represents future minimum rental payments under noncancelable operating leases (in thousands):


Year ended December 31—
2017	$	13,098
2018		11,904
2019		9,666
2020		7,204
2021		5,051
Thereafter		9,107
	$	56,030

Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2016

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,
	2016	2015	2014
Common shares outstanding, end of period	37,209	37,427	37,270
Effect of using weighted average common shares outstanding	126	15	277
Shares used in computing earnings per share—basic	37,335	37,442	37,547
Effect of shares issuable under stock option plans based on the treasury stock method	330	266	147
Effect of restricted and contingently issuable shares	146	160	103
Shares used in computing earnings per share—diluted	37,811	37,868	37,797

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2016

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,
	2016
		Weighted-
		Average
Stock Options	Shares	Exercise Price
Outstanding at beginning of year	724	$	14.69
Granted	102	$	30.36
Exercised	(112)	$	14.11
Forfeited	—	$	—
Expired	—	$	—
Outstanding at end of year	714	$	17.01
Options exercisable at end of year	473

Summary information about stock options outstanding

The following table summarizes information about stock options outstanding at December 31, 2016 (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	12/31/2016	Life	Exercise Price		12/31/2016	Exercise Price
$11.00 - $15.00	361	4.63	$	12.64	361	$	12.64
$15.01 - $20.00	251	7.72	$	17.89	112	$	17.30
$20.01 - $30.36	102	9.23	$	30.36	—	$	—
$11.00 - $30.36	714	6.37	$	17.01	473	$	13.74

Schedule of fair values and the assumptions used for the grants


	Year Ended December 31,
	2016		2015		2014
Weighted-average fair value per share of options granted	$	9.94	$	6.33	$	6.24
Fair value assumptions:
Expected dividend yield		0.97%		1.51%		1.34%
Expected stock price volatility		37.9%		38.4%		45.2%
Risk-free interest rate		1.41%		1.50%		1.91%
Expected term		5.3 years		5.6 years		5.6 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, 2016 and changes for the year ended December 31, 2016 (shares in thousands):


		Weighted-Average
		Grant Date
Stock Options	Shares	Fair Value
Nonvested at December 31, 2015	287	$	6.07
Granted	102	$	9.94
Vested	(148)	$	5.85
Forfeited	—		—
Nonvested at December 31, 2016	241	$	7.83

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,
	2016
		Weighted
		Average Grant
Restricted Stock and Restricted Stock Units	Shares	Date Fair Value
Unvested at beginning of year	149	$	17.48
Granted	85	$	30.25
Vested	(108)	$	20.61
Forfeited	—	$	—
Unvested at end of year	126	$	23.41

Selected Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2016

Selected Quarterly Financial Data (Unaudited)

Schedule of Quarterly Financial Information

Quarterly financial information for the years ended December 31, 2016 and 2015 is summarized as follows (in thousands, except per share data):


	2016
	Q1		Q2		Q3		Q4
Revenue	$	385,942	$	427,538	$	428,760	$	392,100
Gross profit		73,502		89,426		92,816		88,265
Net income including noncontrolling interests		9,841		17,717		20,471		16,867
Net income attributable to Comfort Systems USA, Inc.		9,841		17,717		20,471		16,867
INCOME PER SHARE ATTRIBUTABLE TO COMFORT SYSTEMS USA, INC.:
Basic—
Income from continuing operations	$	0.26	$	0.47	$	0.55	$	0.45
Income from discontinued operations		—		—		—		—
Net income	$	0.26	$	0.47	$	0.55	$	0.45
Diluted—
Income from continuing operations	$	0.26	$	0.47	$	0.54	$	0.45
Income from discontinued operations		—		—		—		—
Net income	$	0.26	$	0.47	$	0.54	$	0.45


	2015
	Q1		Q2		Q3		Q4
Revenue	$	369,547	$	416,567	$	410,565	$	383,840
Gross profit (1)		64,688		82,049		87,465		83,927
Net income including noncontrolling interests		6,889		15,782		19,886		14,883
Net income attributable to Comfort Systems USA, Inc.		5,066		13,404		17,673		13,221
INCOME PER SHARE ATTRIBUTABLE TO COMFORT SYSTEMS USA, INC.:
Basic—
Income from continuing operations	$	0.14	$	0.36	$	0.47	$	0.35
Income from discontinued operations		—		—		—		—
Net income	$	0.14	$	0.36	$	0.47	$	0.35
Diluted—
Income from continuing operations	$	0.13	$	0.35	$	0.46	$	0.35
Income from discontinued operations		—		—		—		—
Net income	$	0.13	$	0.35	$	0.46	$	0.35

(1)

In the fourth quarter of 2015, we recognized a $3.4 million project gain related to change orders we received.

Business and Organization (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Business and Organization
Revenue	$ 392,100	$ 428,760	$ 427,538	$ 385,942	$ 383,840	$ 410,565	$ 416,567	$ 369,547	$ 1,634,340	$ 1,580,519	$ 1,410,795
Percentage of revenue attributable to services									100.00%
Installation of systems in newly constructed facilities
Business and Organization
Percentage of revenue attributable to services									40.00%
Maintenance, repair and replacement services
Business and Organization
Percentage of revenue attributable to services									60.00%
HVAC
Business and Organization
Revenue									$ 1,225,755
Percentage of revenue attributable to services									75.00%
Plumbing
Business and Organization
Revenue									$ 245,151
Percentage of revenue attributable to services									15.00%
Building Automation Control Systems
Business and Organization
Revenue									$ 98,060
Percentage of revenue attributable to services									6.00%
Other
Business and Organization
Revenue									$ 65,374
Percentage of revenue attributable to services									4.00%

Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands		3 Months Ended		12 Months Ended
	Jan. 01, 2016	Mar. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Use of Estimates
Gain Loss From Project			$ 3,400		$ 3,400	$ 4,400
Cash paid for:
Interest				$ 1,864	1,408	1,764
Income taxes paid				$ 29,349	35,538	15,366
Revenue Recognition
Percentage of revenue earned on a project basis				82.00%
Contracts in progress
Costs incurred on contracts in progress			1,135,279	$ 1,116,182	1,135,279
Estimated earnings, net of losses			188,243	207,252	188,243
Less-Billings to date			1,377,581	1,378,050	1,377,581
Contracts in progress			(54,059)	(54,616)	(54,059)
Costs and estimated earnings in excess of billings			31,338	29,369	31,338
Billings in excess of costs and estimated earnings			85,397	$ 83,985	85,397
Period during which progress billings or contract price can be withheld until completion of work				6 months
Retention receivable			51,600	$ 60,700	51,600
Retention payable			7,800	$ 10,100	7,800
Warranty Costs
Labor warranty period after servicing of existing HVAC system				30 days
Income Taxes
Federal statutory income taxes rate (as a percent)				35.00%
Recent Accounting Pronouncements
Deferred tax liabilities			$ 1,810	$ 2,289	1,810
Effect of share-based compensation of excess tax benefit in provision for income taxes				1,900	2,100	1,800
Impact on retained earnings for minimum statutory withholding tax requirement due to amendments				$ 1,304	937	531
Excess tax benefit of stock-based compensation					$ 1,240	$ 115
Accounting Standards Update 2016-09 \| Adjustments for New Accounting Principle, Early Adoption
Recent Accounting Pronouncements
Effect of share-based compensation of excess tax benefit in provision for income taxes	$ 100
Excess tax benefit of stock-based compensation, operating activities		$ 100
Excess tax benefit of stock-based compensation		$ (100)
Accounting Standards Update 2016-09 \| Adjustments for New Accounting Principle, Early Adoption \| Maximum
Recent Accounting Pronouncements
Cumulative effect adjustment to retained earnings for increase to stock compensation expense	$ 100

Summary of Significant Accounting Policies - Risk (Details) - Revenue - Customer concentration	12 Months Ended
	Dec. 31, 2016 item
Concentrations of Credit Risk
Number of single customers accounting for more than threshold concentration risk percentage	0
Minimum
Concentrations of Credit Risk
Single customer, percentage of revenue	3.00%

Fair Value Measurements (Details) $ in Thousands	12 Months Ended
Fair Value Measurements (Details) $ in Thousands	Dec. 31, 2016 USD ($) item	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Fair Value Measurements
Number of employees covered under life insurance policies \| item	48
Combined face value of life insurance policies	$ 44,200
Cash surrender value	3,700	$ 3,600
Reconciliation of the fair value of contingent earn-out obligations that use significant unobservable inputs (Level 3)
Goodwill, Impairment Loss			$ 727
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	450
Issuances	3,240
Settlements	(428)
Adjustments to fair value	(731)
Balance at end of period	2,531	450
Significant Unobservable Inputs (Level 3)
Reconciliation of the fair value of contingent earn-out obligations that use significant unobservable inputs (Level 3)
Goodwill, Impairment Loss	0	$ 0	$ 700
Recurring basis \| Total
Fair Value Measurements
Cash and cash equivalents	32,074
Life insurance - cash surrender value	3,697
Contingent earn-out obligations	2,531
Recurring basis \| Quoted Market Prices In Active Markets for Identical Assets (Level 1)
Fair Value Measurements
Cash and cash equivalents	32,074
Recurring basis \| Fair Value Measurements at Reporting Date Using Significant Other Observable Inputs (Level 2)
Fair Value Measurements
Life insurance - cash surrender value	3,697
Recurring basis \| Significant Unobservable Inputs (Level 3)
Fair Value Measurements
Contingent earn-out obligations	$ 2,531

Acquisitions (Details) $ in Thousands		3 Months Ended	12 Months Ended
Acquisitions (Details) $ in Thousands	Jan. 01, 2016 USD ($)	Mar. 31, 2016 item	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Acquisitions
Number of acquisitions \| item		2
Goodwill on acquisition			$ 149,208	$ 143,874	$ 140,341
Environmental Air Systems
Acquisitions
Interest acquired (as a percent)	40.00%
Total purchase price	$ 46,600
Purchase price paid in cash	$ 42,000
Shoffner
Acquisitions
Interest acquired (as a percent)		100.00%
Total purchase price			19,800
Purchase price paid in cash			15,500
Revenue in consolidated results			71,900
Amount allocated to goodwill and identifiable intangible assets for acquisitions			14,800
Other Acquisitions
Acquisitions
Total purchase price			$ 100	$ 8,300

Discontinued Operations (Details) - USD ($) $ in Thousands	12 Months Ended
Discontinued Operations (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2014
Discontinued Operations
After-tax loss from discontinued operations		$ (15)
Interest expense allocated to discontinued operations	$ 0
Revenue and pre-tax income (loss) related to discontinued operations
Revenue		7
Pre-tax loss		(25)
Operation located in Delaware \| Maximum
Discontinued Operations
After-tax loss from discontinued operations		$ (100)

Goodwill and Identifiable Intangible Assets, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Goodwill [Roll Forward]
Balance at the beginning of year	$ 143,874	$ 140,341
Additions	5,334	3,533
Balance at end of period	$ 149,208	$ 143,874	$ 140,341
Impairment Testing
Goodwill impairment			$ 727
Impairment testing, Scenario one
Impairment Testing
Impairment testing, discounted cash flow analysis weightage assigned	50.00%
Impairment testing, Scenario two
Impairment Testing
Impairment testing, public company approach weightage assigned	50.00%

Goodwill and Identifiable Intangible Assets, Net - IdentifiableIntangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Identifiable Intangible Assets, Net
Gross Book Value	$ 95,360	$ 85,819
Accumulated Amortization	(52,925)	(44,740)
Amortization of identifiable intangible assets	8,185	7,481	$ 7,653
Future amortization expense of identifiable intangible assets
2017	5,702
2018	4,861
2019	4,246
2020	3,751
2021	3,300
Thereafter	20,575
Total	42,435
Customer relationships
Identifiable Intangible Assets, Net
Gross Book Value	57,230	53,334
Accumulated Amortization	$ (36,758)	(31,960)
Customer relationships \| Minimum
Identifiable Intangible Assets, Net
Estimated Useful Lives in Years	1 year
Customer relationships \| Maximum
Identifiable Intangible Assets, Net
Estimated Useful Lives in Years	15 years
Backlog
Identifiable Intangible Assets, Net
Gross Book Value	$ 3,600	1,600
Accumulated Amortization	$ (3,433)	(1,412)
Backlog \| Minimum
Identifiable Intangible Assets, Net
Estimated Useful Lives in Years	1 year
Backlog \| Maximum
Identifiable Intangible Assets, Net
Estimated Useful Lives in Years	2 years
Noncompete agreements
Identifiable Intangible Assets, Net
Gross Book Value	$ 2,890	2,890
Accumulated Amortization	$ (2,890)	(2,890)
Noncompete agreements \| Minimum
Identifiable Intangible Assets, Net
Estimated Useful Lives in Years	2 years
Noncompete agreements \| Maximum
Identifiable Intangible Assets, Net
Estimated Useful Lives in Years	7 years
Tradenames
Identifiable Intangible Assets, Net
Gross Book Value	$ 31,640	27,995
Accumulated Amortization	$ (9,844)	$ (8,478)
Tradenames \| Minimum
Identifiable Intangible Assets, Net
Estimated Useful Lives in Years	2 years
Tradenames \| Maximum
Identifiable Intangible Assets, Net
Estimated Useful Lives in Years	25 years

Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property and equipment
Property and equipment, gross	$ 165,331	$ 148,455
Less-Accumulated depreciation	(97,136)	(87,642)
Property and equipment, net	68,195	60,813
Depreciation expense	18,000	15,900	$ 13,700
Land
Property and equipment
Property and equipment, gross	2,745	2,745
Transportation equipment
Property and equipment
Property and equipment, gross	$ 74,137	64,951
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	$ 27,843	25,118
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	$ 20,791	21,141
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	$ 35,166	30,319
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	$ 4,224	$ 4,181
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	$ 425

Detail of Certain Balance Sheet Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Activity in allowance for doubtful accounts
Balance at beginning of year	$ 5,158	$ 4,379	$ 4,460
Bad debt expense (benefit)	(27)	1,552	1,275
Deductions for uncollectible receivables written off, net of recoveries	(876)	(798)	(1,650)
Allowance for doubtful accounts of acquired companies at date of acquisition	33	25	294
Balance at end of year	4,288	5,158	$ 4,379
Other current liabilities
Accrued warranty costs	6,702	7,746
Accrued job losses	1,269	1,365
Accrued sales and use tax	1,973	2,216
Deferred revenue	5,257	2,175
Liabilities due to former owners	4,196	2,650
Other current liabilities	14,864	12,525
Total other current liabilities	$ 34,261	$ 28,677

Long Term Debt Obligations (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Long-Term Debt Obligations
Total debt	$ 2,811	$ 11,507
Less - current portion	(763)	(751)
Total long-term portion of debt	2,048	10,756
Revolving credit facility
Long-Term Debt Obligations
Total debt		10,000
Notes to former owners
Long-Term Debt Obligations
Total debt	2,250	1,000
Other debt
Long-Term Debt Obligations
Total debt	305
Capital lease obligations
Long-Term Debt Obligations
Total debt	$ 256	$ 507

Long-Term Debt Obligations - Future Payments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Future principal payments of long-term debt
2017	$ 763
2018	1,046
2019	1,002
Total debt	2,811	$ 11,507
Interest expense
Interest expense on notes to former owners	70	25	$ 38
Interest expense on borrowings and unused commitment fees	1,251	692	790
Letter of credit fees	657	719	747
Amortization of debt financing costs	367	317	283
Total	$ 2,345	1,753	$ 1,858
Revolving credit facility
Future principal payments of long-term debt
Total debt		$ 10,000

Long-Term Debt Obligations-Other (Details) $ in Thousands	3 Months Ended								12 Months Ended
Long-Term Debt Obligations-Other (Details) $ in Thousands	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($) item	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2016 USD ($) item	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Feb. 22, 2016 USD ($)	Feb. 21, 2016 USD ($)
Long-Term Debt Obligations
Line of credit borrowing capacity accordion option												$ 100,000
Reconciliation of Earnings before Interest Tax Depreciation and Amortization to Net Income
Net income including noncontrolling interests	$ 16,867	$ 20,471	$ 17,717	$ 9,841	$ 14,883	$ 19,886	$ 15,782	$ 6,889	$ 64,896	$ 57,440	$ 28,599
Income tax expense									$ 36,165	31,224	$ 11,614
Principal financial covenants
Leverage ratio	3.00								3.00
Other disclosures
Oustanding balance	$ 2,811				11,507				$ 2,811	11,507
Capital lease obligation pertaining to acquisition	300								300
Current portion of capital lease obligations	163				251				163	251
Number of acquisitions \| item				2
Shoffner
Other disclosures
Debt acquired related to coil line duct processing system	400								400
Outstanding balance	300								300
Current debt	100								$ 100
London Interbank Offered Rate (LIBOR) \| Shoffner
Market rates relating to interest options
Interest rate margin (as a percent)									2.25%
Additional per annum interest margin added under:
Additional per annum interest margin (as a percent)									2.25%
Revolving credit facility
Long-Term Debt Obligations
Borrowing capacity												$ 325,000	$ 250,000
Financing and professional cost	800								$ 800
Unamortized costs	1,100								1,100
Letters of credit amount outstanding	41,500								41,500
Credit available	283,500								283,500
Book value of assets pledged as collateral	$ 41,500								$ 41,500
Number of quarters of net earnings used for the calculation of the credit facility adjusted EBITDA \| item									4
Reconciliation of Earnings before Interest Tax Depreciation and Amortization to Net Income
Net income including noncontrolling interests									$ 64,896
Income tax expense									(36,165)
Interest expense, net									2,336
Depreciation and amortization expense									26,166
Stock-based compensation									5,041
Pre-acquisition results of acquired companies, as defined under the Facility									10
Credit Facility Adjusted EBITDA									$ 134,614
Principal financial covenants
Leverage ratio	0.02								0.02
Fixed charge coverage ratio	27.84								27.84
Number of quarters of capital expenditures, tax provision, dividends and stock repurchase payments used for calculation of fixed charge coverage ratio \| item									4
Number of interest rate options \| item									2
Period of Credit Facility Adjusted EBITDA for determining additional margins									12 months
Additional per annum interest margin added under:
Weighted average interest rate (as a percent)	1.80%								1.80%
Other disclosures
Oustanding balance					10,000					10,000
Revolving credit facility \| Through maturity
Principal financial covenants
Leverage ratio	2.75								2.75
Revolving credit facility \| Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: Less than 0.75
Additional per annum interest margin added under:
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: 0.75 to 1.50
Additional per annum interest margin added under:
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: 1.50 to 2.25
Additional per annum interest margin added under:
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: 2.25 or greater
Additional per annum interest margin added under:
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	2.00								2.00
Revolving credit facility \| Minimum \| Covenant Requirement
Principal financial covenants
Net leverage ratio used as basis for other restrictions	2.00								2.00
Revolving credit facility \| Maximum
Principal financial covenants
Net leverage ratio after giving effect to stock repurchases for calculation of the fixed charge coverage ratio	1.50								1.50
Permitted amount of acquisitions per transaction	$ 30,000								$ 30,000
Aggregate purchase price of current acquisition and acquisitions in the preceding 12 month period for determining permitted amount of acquisition per transaction	$ 65,000								$ 65,000
Revolving credit facility \| Maximum \| Covenant Requirement
Principal financial covenants
Net leverage ratio used to determine exclusion of stock repurchases and the payment of dividends for calculation of the fixed charge coverage ratio	1.50								1.50
Revolving credit facility \| Maximum \| Stock Repurchases Through September 30, 2015
Principal financial covenants
Amount of stock repurchases to maintain maximum net leverage ratio									$ 25,000
Revolving credit facility \| Maximum \| Stock Repurchases After February 22, 2016 And On Or Before December 31, 2017
Principal financial covenants
Amount of stock repurchases to maintain maximum net leverage ratio									$ 25,000
Revolving credit facility \| Base rate \| Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: Less than 0.75
Market rates relating to interest options
Interest rate margin (as a percent)									0.25%
Additional per annum interest margin added under:
Additional per annum interest margin (as a percent)									0.25%
Revolving credit facility \| Base rate \| Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 0.75 to 1.50
Market rates relating to interest options
Interest rate margin (as a percent)									0.50%
Additional per annum interest margin added under:
Additional per annum interest margin (as a percent)									0.50%
Revolving credit facility \| Base rate \| Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 1.50 to 2.25
Market rates relating to interest options
Interest rate margin (as a percent)									0.75%
Additional per annum interest margin added under:
Additional per annum interest margin (as a percent)									0.75%
Revolving credit facility \| Base rate \| Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 2.25 or greater
Market rates relating to interest options
Interest rate margin (as a percent)									1.00%
Additional per annum interest margin added under:
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 0.75
Market rates relating to interest options
Interest rate margin (as a percent)									1.25%
Additional per annum interest margin added under:
Additional per annum interest margin (as a percent)									1.25%
Revolving credit facility \| Eurodollar rate \| Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 0.75 to 1.50
Market rates relating to interest options
Interest rate margin (as a percent)									1.50%
Additional per annum interest margin added under:
Additional per annum interest margin (as a percent)									1.50%
Revolving credit facility \| Eurodollar rate \| Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 1.50 to 2.25
Market rates relating to interest options
Interest rate margin (as a percent)									1.75%
Additional per annum interest margin added under:
Additional per annum interest margin (as a percent)									1.75%
Revolving credit facility \| Eurodollar rate \| Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 2.25 or greater
Market rates relating to interest options
Interest rate margin (as a percent)									2.00%
Additional per annum interest margin added under:
Additional per annum interest margin (as a percent)									2.00%
Notes to former owners
Other disclosures
Oustanding balance	$ 2,250				$ 1,000				$ 2,250	$ 1,000
Notes to former owners \| Shoffner
Other disclosures
Oustanding balance	$ 1,800								$ 1,800
Weighted average interest rate (as a percent)	3.00%								3.00%
Notes to former owners \| Other Acquisitions
Other disclosures
Oustanding balance	$ 500								$ 500
Weighted average interest rate (as a percent)	2.50%								2.50%
Other debt
Other disclosures
Oustanding balance	$ 305								$ 305
Other debt \| Dyna Ten
Other disclosures
Capital lease obligation pertaining to acquisition	300								300
Current portion of capital lease obligations	$ 200								$ 200
Number of acquisitions \| item									1
Federal Funds Rate \| Revolving credit facility \| Base rate
Market rates relating to interest options
Interest rate margin (as a percent)									0.50%
Market rate (as a percent)	1.16%								1.16%
Additional per annum interest margin added under:
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)	3.75%								3.75%
One-month LIBOR \| Revolving credit facility \| Base rate
Market rates relating to interest options
Interest rate margin (as a percent)									1.00%
Market rate (as a percent)	1.77%								1.77%
Additional per annum interest margin added under:
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)	0.77%								0.77%
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)	1.32%								1.32%

Income Taxes - Provision (Details) - USD ($) $ in Thousands	12 Months Ended
Income Taxes - Provision (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current-
Federal	$ 32,721	$ 27,564	$ 13,402
State and Puerto Rico	4,683	4,065	2,810
Total	37,404	31,629	16,212
Deferred-
Federal	(2,101)	(1,481)	(308)
State and Puerto Rico	862	1,076	(4,290)
Total	(1,239)	(405)	(4,598)
Provision for income taxes	$ 36,165	$ 31,224	$ 11,614

Income Taxes - Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Taxes
Federal statutory income taxes rate (as a percent)	35.00%
Income tax expense at the statutory rate of 35%	$ 35,371	$ 31,032	$ 14,080
Changes resulting from-
State income taxes, net of federal tax effect	4,262	3,432	1,653
Increase (decrease) in valuation allowance	(1,254)	463	(1,944)
Increase (decrease) in tax contingency reserves	20	(72)	(40)
Increase (decrease) from noncontrolling interests		(2,827)	(1,938)
Non-deductible expenses	825	751	704
Equity based stock compensation deduction	(885)
Production activity deduction	(2,026)	(1,701)	(694)
Purchase accounting adjustments			(46)
Other	(148)	146	(161)
Provision for income taxes	$ 36,165	$ 31,224	$ 11,614

Income Taxes - Deferred Tax Assets (Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred income tax assets-
Accounts receivable and allowance for doubtful accounts	$ 1,627	$ 1,889
Stock compensation	3,036	3,080
Accrued liabilities and expenses	23,000	19,174
State net operating loss carryforwards	5,053	6,781
Goodwill	875
Other	759	830
Total deferred income tax assets	34,350	31,754
Deferred income tax liabilities-
Property and equipment	(4,398)	(5,572)
Long-term contracts	(637)	(728)
Goodwill		(6,037)
Intangible assets	(737)	(156)
Other	(513)	(357)
Total deferred income tax liabilities	(6,285)	(12,850)
Less-Valuation allowance	(3,184)	(4,438)
Net deferred income tax assets	24,881	14,466
Deferred income tax assets-
Deferred income tax assets	27,170	16,276
Deferred income tax liabilities-
Deferred tax liabilities	$ 2,289	$ 1,810

Income Taxes - Loss Carryforwards and Other (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating loss carryforwards
Unrecognized tax benefits that would impact effective tax rate	$ 200	$ 200
Interest and penalties accrued	400	300
Reconciliation of the beginning and ending amount of unrecognized tax benefits
Balance at the beginning of year	240	343	$ 413
Additions based on tax positions related to the current year	0	0	0
Additions for tax positions of prior years	0	0	0
Reductions for tax positions of prior years	0	(103)	(70)
Settlements	0	0	0
Balance at the end of year	240	240	$ 343
Valuation allowance	$ 3,184	4,438
State and Puerto Rico
Reconciliation of the beginning and ending amount of unrecognized tax benefits
Future tax benefits		5,100
Net operating loss carryforwards		70,400
Valuation allowance		3,200
Increase in valuation allowance		1,300
Deferred tax assets net of valuation allowance		$ 2,200

Employee Benefit Plans (Details) $ in Thousands	12 Months Ended
Employee Benefit Plans (Details) $ in Thousands	Dec. 31, 2016 USD ($) item	Dec. 31, 2015 USD ($) item	Dec. 31, 2014 USD ($)
Employee Benefit Plans
Percentage of contribution of covered employee's salaries or wages	2.50%
Contribution	$ 7,800	$ 7,100	$ 6,100
Amount payable to plan	$ 200	$ 100
Number of employees who are union members \| item	5	11
Contributions made to multi-employer pension plans	$ 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	$ 4,000	$ 3,300

Commitments and Contingencies - Minimum Lease Payments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Leases
Rent expense	$ 20,600	$ 20,600	$ 17,800
Capital lease obligation pertaining to acquisition in northern Texas	300
Future minimum rental payments under noncancelable operating leases
2017	13,098
2018	11,904
2019	9,666
2020	7,204
2021	5,051
Thereafter	9,107
Total future minimum rental payments	$ 56,030
Lease buildings \| Minimum
Leases
Lease term	3 years
Lease buildings \| Maximum
Leases
Lease term	10 years
Lease buildings \| Previous owners
Leases
Rent expense	$ 5,100	$ 5,400	$ 3,800

Commitments and Contingencies - Bonds (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($)
British Petroleum
Commitments and Contingencies
Gain on the claim settlement	$ 0.6
Surety \| Minimum
Surety
Percentage of business which has required bonds	20.00%
Surety \| Maximum
Surety
Percentage of business which has required bonds	30.00%

Commitments and Contingencies - Self Insurance (Details)	Dec. 31, 2016 USD ($) item
Workers Compensation
Self-Insurance
Per incident deductible amount	$ 1,000,000
Amount of loss fully insured above per incident deductible amount.	1,000,000
Employer's Liability
Self-Insurance
Per incident deductible amount	1,000,000
Employer's Liability \| Maximum
Self-Insurance
Amount of excess loss insurance covered	100,000,000
General Liability
Self-Insurance
Per incident deductible amount	1,000,000
Amount of loss fully insured above per incident deductible amount.	1,000,000
General Liability \| Maximum
Self-Insurance
Amount of excess loss insurance covered	100,000,000
Auto Liability
Self-Insurance
Per incident deductible amount	500,000
Amount of loss fully insured above per incident deductible amount.	1,500,000
Auto Liability \| Maximum
Self-Insurance
Amount of excess loss insurance covered	$ 100,000,000
Employee Medical
Self-Insurance
Number of medical plans \| item	2
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

Stockholders' Equity- Incentive and Other (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended	105 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Aug. 11, 2016	May 31, 2012	Mar. 29, 2007
Share Repurchase Program
Number of shares of outstanding common stock authorized to be acquired under a stock repurchase program	8.1		0.6		1.0
Share repurchase (in shares)		7.3
Average price (in dollars per share)	$ 28.44	$ 13.02
Repurchased carrying basis	$ 13.1
2012 Equity Incentive Plan
Stockholder's Equity
Number of shares authorized and reserved for issuance				5.1
Number of shares available for issuance	3.2
Maximum
Share Repurchase Program
Share repurchase (in shares)	0.5

Stockholders' Equity- Anti-dilutive stock options (Details) - shares shares in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Stock Options
Earnings Per Share
Anti-dilutive securities excluded from computation of earnings per share amount (in shares)	0.1	0.0	0.2

Stockholders' Equity-Number of Shares (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
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	37,209	37,427	37,270
Effect of using weighted average common shares outstanding	(126)	(15)	(277)
Shares used in computing earnings per share - basic	37,335	37,442	37,547
Effect of shares issuable under stock option plans based on the treasury stock method	330	266	147
Effect of restricted and contingently issuable shares	146	160	103
Shares used in computing earnings per share - diluted	37,811	37,868	37,797

Stock-Based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Stock-Based Compensation
Stock-based compensation expense	$ 5.0	$ 5.6	$ 4.8
Income tax benefit	$ 1.9	$ 2.1	1.8
Stock Options
Shares
Outstanding at beginning of year (in shares)	724
Granted (in shares)	102
Issuance of shares for options exercised including tax benefit (in shares)	(112)
Outstanding at end of year (in shares)	714	724
Options exercisable at end of year (in shares)	473
Weighted-Average Exercise Price
Outstanding at beginning of year (in dollars per share)	$ 14.69
Granted (in dollars per share)	30.36
Exercised (in dollars per share)	14.11
Outstanding at end of year (in dollars per share)	$ 17.01	$ 14.69
Other information
Intrinsic value of options exercised	$ 1.9	$ 3.9	$ 0.4
Weighted-average remaining contractual term of options exercisable	5 years 3 months 18 days
Aggregate intrinsic value of options exercisable	$ 9.2
Number of options that are vested and expected to vest (in shares)	700
Weighted average exercise price of options that are vested and expected to vest (in dollars per share)	$ 17.01
Weighted-average remaining contractual term of options that are vested and expected to vest	6 years 4 months 24 days
Aggregate intrinsic value of options that are vested and expected to vest	$ 11.6

Stock-Based Compensation - Stock Option Plan Activity (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2016 $ / shares shares
$11.00 - $15.00
Stock-Based Compensation
Exercise price, low end of range (in dollars per share)	$ 11.00
Exercise price, high end of range (in dollars per share)	15.00
$15.01 - $20.00
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)	20.00
$20.01 - $30.36
Stock-Based Compensation
Exercise price, low end of range (in dollars per share)	20.01
Exercise price, high end of range (in dollars per share)	30.36
$11.00 - $30.36
Stock-Based Compensation
Exercise price, low end of range (in dollars per share)	11.00
Exercise price, high end of range (in dollars per share)	$ 30.36
Stock Options \| $11.00 - $15.00
Options Outstanding
Number of Shares \| shares	361
Weighted Average Remaining Contractual Life	4 years 7 months 17 days
Weighted Average Exercise Price (in dollars per share)	$ 12.64
Options Exercisable
Number of Shares \| shares	361
Weighted Average Exercise Price (in dollars per share)	$ 12.64
Stock Options \| $15.01 - $20.00
Options Outstanding
Number of Shares \| shares	251
Weighted Average Remaining Contractual Life	7 years 8 months 19 days
Weighted Average Exercise Price (in dollars per share)	$ 17.89
Options Exercisable
Number of Shares \| shares	112
Weighted Average Exercise Price (in dollars per share)	$ 17.30
Stock Options \| $20.01 - $30.36
Options Outstanding
Number of Shares \| shares	102
Weighted Average Remaining Contractual Life	9 years 2 months 23 days
Weighted Average Exercise Price (in dollars per share)	$ 30.36
Stock Options \| $11.00 - $30.36
Options Outstanding
Number of Shares \| shares	714
Weighted Average Remaining Contractual Life	6 years 4 months 13 days
Weighted Average Exercise Price (in dollars per share)	$ 17.01
Options Exercisable
Number of Shares \| shares	473
Weighted Average Exercise Price (in dollars per share)	$ 13.74

Stock-Based Compensation - Fair Value Assumptions (Details) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) item $ / shares shares	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($) $ / shares
Additional information
Accrued compensation	$ 61,712	$ 54,079
Allocated Share-based Compensation Expense	$ 5,000	$ 5,600	$ 4,800
Stock Options
Stock-Based Compensation
Weighted-average fair value per share of options granted (in dollars per share) \| $ / shares	$ 9.94	$ 6.33	$ 6.24
Fair value assumptions:
Expected dividend yield (as a percent)	0.97%	1.51%	1.34%
Expected stock price volatility (as a percent)	37.90%	38.40%	45.20%
Risk-free interest rate (as a percent)	1.41%	1.50%	1.91%
Expected term	5 years 3 months 18 days	5 years 7 months 6 days	5 years 7 months 6 days
Other information
Vesting period	3 years
Total fair value of options vested	$ 900
Nonvested Options, Shares
Nonvested at beginning of year (in shares) \| shares	287
Granted (in shares) \| shares	102
Vested (in shares) \| shares	(148)
Nonvested at end of year (in shares) \| shares	241	287
Nonvested Options, Weighted-Average Grant Date Fair Value
Nonvested at beginning of year (in dollars per share) \| $ / shares	$ 6.07
Granted (in dollars per share) \| $ / shares	9.94	$ 6.33	$ 6.24
Vested (in dollars per share) \| $ / shares	5.85
Nonvested at end of year (in dollars per share) \| $ / shares	$ 7.83	$ 6.07
Additional information
Compensation expense yet to be recognized	$ 800
Weighted-average period over which compensation cost will be recognized	1 year 6 months
Stock Options \| Minimum
Other information
Sum of age and years of service for accelerated vesting on retirement of certain stock options and restricted stock awards	75 years
Restricted Stock and Restricted Stock Units
Shares
Unvested at beginning of year (in shares) \| shares	149
Granted (in shares) \| shares	85
Vested (in shares) \| shares	(108)
Unvested at end of year (in shares) \| shares	126	149
Weighted Average Grant Date Fair Value
Unvested at beginning of year (in dollars per share) \| $ / shares	$ 17.48
Granted (in dollars per share) \| $ / shares	30.25	$ 20.64	15.80
Vested (in dollars per share) \| $ / shares	20.61
Unvested at end of year (in dollars per share) \| $ / shares	$ 23.41	17.48
Additional information
Compensation expense yet to be recognized	$ 1,300
Weighted-average period over which compensation cost will be recognized	1 year 7 months 6 days
Fair value of shares vested	$ 2,200
Weighted-average fair value (in dollars per share) \| $ / shares	$ 30.25	$ 20.64	$ 15.80
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Vested	$ 3,600	$ 3,400	$ 2,900
Performance Stock Units
Other information
Vesting period	3 years
Additional information
Compensation expense yet to be recognized	$ 1,500
Weighted-average period over which compensation cost will be recognized	1 year 1 month 6 days
Period for which shareholder return is compared with peer group for units determined by EPS performance	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%
Calculated fair market value	$ 4,800
Value of PSUs granted	1,800
Allocated Share-based Compensation Expense	$ 1,600	$ 2,600	$ 1,800
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
Restricted Stock \| Minimum
Other information
Sum of age and years of service for accelerated vesting on retirement of certain stock options and restricted stock awards	75 years

Selected Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Selected Quarterly Financial Information [Abstract]
Revenue	$ 392,100	$ 428,760	$ 427,538	$ 385,942	$ 383,840	$ 410,565	$ 416,567	$ 369,547	$ 1,634,340	$ 1,580,519	$ 1,410,795
Gross Profit	88,265	92,816	89,426	73,502	83,927	87,465	82,049	64,688	344,009	318,129	249,771
Net income including noncontrolling interests	16,867	20,471	17,717	9,841	14,883	19,886	15,782	6,889	64,896	57,440	28,599
Net income attributable to Comfort Systems USA, Inc.	$ 16,867	$ 20,471	$ 17,717	$ 9,841	$ 13,221	$ 17,673	$ 13,404	$ 5,066	$ 64,896	$ 49,364	$ 23,063
Basic-
Income from continuing operations (in dollars per share)	$ 0.45	$ 0.55	$ 0.47	$ 0.26	$ 0.35	$ 0.47	$ 0.36	$ 0.14	$ 1.74	$ 1.32	$ 0.61
Net income (in dollars per share)	0.45	0.55	0.47	0.26	0.35	0.47	0.36	0.14	1.74	1.32	0.61
Diluted-
Income from continuing operations (in dollars per share)	0.45	0.54	0.47	0.26	0.35	0.46	0.35	0.13	1.72	1.30	0.61
Net income (in dollars per share)	$ 0.45	$ 0.54	$ 0.47	$ 0.26	$ 0.35	$ 0.46	$ 0.35	$ 0.13	$ 1.72	$ 1.30	$ 0.61
Gain Loss From Project					$ 3,400					$ 3,400	$ 4,400

Subsequent Events (Details) - Subsequent events - BCH $ in Thousands	Feb. 21, 2017 USD ($) installment
Subsequent Events
Fair value of consideration transferred	$ 100,000
Purchase price paid in cash	85,700
Promissory note payable	$ 14,300
Number of installments payable for promissory note \| installment	2
Promissory note payable in each installment	$ 7,150