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Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2016	Apr. 20, 2016
Document and Entity Information
Entity Registrant Name	COMFORT SYSTEMS USA INC
Entity Central Index Key	0001035983
Document Type	10-Q
Document Period End Date	Mar. 31, 2016
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		37,444,146
Document Fiscal Year Focus	2016
Document Fiscal Period Focus	Q1

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
CURRENT ASSETS:
Cash and cash equivalents	$ 43,540	$ 56,464
Accounts receivable, less allowance for doubtful accounts of $4,998 and $5,158, respectively	306,111	302,052
Other receivables	15,181	20,642
Inventories	9,783	7,941
Prepaid expenses and other	5,719	5,836
Costs and estimated earnings in excess of billings	34,350	31,338
Total current assets	414,684	424,273
PROPERTY AND EQUIPMENT, NET	62,557	60,813
GOODWILL	147,297	143,874
IDENTIFIABLE INTANGIBLE ASSETS, NET	49,140	41,079
DEFERRED INCOME TAX ASSETS, NET	29,240	16,276
OTHER NONCURRENT ASSETS	6,051	5,279
Total assets	708,969	691,594
CURRENT LIABILITIES:
Current maturities of long-term debt	600	500
Current maturities of long-term capital lease obligations	241	251
Accounts payable	106,536	106,684
Accrued compensation and benefits	50,506	54,079
Billings in excess of costs and estimated earnings	83,810	85,397
Accrued self-insurance	29,863	29,803
Other current liabilities	35,320	28,677
Total current liabilities	306,876	305,391
LONG-TERM DEBT	53,530	10,500
LONG-TERM CAPITAL LEASE OBLIGATIONS	200	256
DEFERRED INCOME TAX LIABILITIES	1,810	1,810
OTHER LONG-TERM LIABILITIES	8,479	8,632
Total liabilities	370,895	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, 3,730,986 and 3,696,781 shares, respectively	(49,118)	(46,845)
Additional paid-in capital	310,062	323,765
Retained earnings	76,719	69,390
Comfort Systems USA, Inc. stockholders' equity	338,074	346,721
Noncontrolling interests		18,284
Total stockholders' equity	338,074	365,005
Total liabilities and stockholders' equity	$ 708,969	$ 691,594

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
CONSOLIDATED BALANCE SHEETS
Accounts receivable, allowance for doubtful accounts (in dollars)	$ 4,998	$ 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	3,730,986	3,696,781

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
CONSOLIDATED STATEMENTS OF OPERATIONS
REVENUE	$ 385,942	$ 369,547
COST OF SERVICES	312,440	304,859
Gross profit	73,502	64,688
SELLING, GENERAL AND ADMINISTRATIVE EXPENSES	58,181	53,696
GAIN ON SALE OF ASSETS	(145)	(176)
Operating income	15,466	11,168
OTHER INCOME (EXPENSE):
Interest income	1	1
Interest expense	(701)	(505)
Other	486	18
Other income (expense)	(214)	(486)
INCOME BEFORE INCOME TAXES	15,252	10,682
INCOME TAX EXPENSE	5,497	3,793
NET INCOME INCLUDING NONCONTROLLING INTERESTS	9,755	6,889
Less: Net income attributable to noncontrolling interests		1,823
NET INCOME ATTRIBUTABLE TO COMFORT SYSTEMS USA, INC.	$ 9,755	$ 5,066
Basic-
Net income (loss) (in dollars per share)	$ 0.26	$ 0.14
Diluted-
Net income (in dollars per share)	$ 0.26	$ 0.13
SHARES USED IN COMPUTING INCOME PER SHARE:
Basic (in shares)	37,344	37,281
Diluted (in shares)	37,730	37,605
DIVIDENDS PER SHARE (in dollars per share)	$ 0.065	$ 0.060

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, 2014	$ 411	$ (43,598)	$ 320,084	$ 29,384	$ 15,112	$ 321,393
BALANCE (in shares) at Dec. 31, 2014	41,123,365
BALANCE (in shares) at Dec. 31, 2014		(3,853,586)
Increase (Decrease) in Stockholders' Equity
Net income						$ 6,889
BALANCE (in shares) at Mar. 31, 2015						37,307,000
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
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 including tax benefit		$ 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
BALANCE (in shares) at Dec. 31, 2015		(3,696,781)				(3,696,781)
Increase (Decrease) in Stockholders' Equity
Net income				9,755		$ 9,755
Issuance of Stock:
Issuance of shares for options exercised including tax benefit		$ 278	92			370
Issuance of shares for options exercised including tax benefit (in shares)		(21,244)
Issuance of restricted stock & performance stock		$ 851	1,125			1,976
Issuance of restricted stock & performance stock (in shares)		(65,086)
Shares received in lieu of tax withholding payment on vested restricted stock		$ (562)				(562)
Shares received in lieu of tax withholding payment on vested restricted stock (in shares)		18,506
Stock-based compensation			990			990
Dividends				(2,426)		(2,426)
Share repurchase		$ (2,840)				(2,840)
Share repurchase (in shares)		102,029
Acquisition of noncontrolling interests			15,910		$ 18,284	34,194
BALANCE at Mar. 31, 2016	$ 411	$ (49,118)	$ 310,062	$ 76,719		$ 338,074
BALANCE (in shares) at Mar. 31, 2016	41,123,365					37,392,000
BALANCE (in shares) at Mar. 31, 2016		(3,730,986)				(3,730,986)

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income including noncontrolling interests	$ 9,755	$ 6,889
Adjustments to reconcile net income to net cash provided by (used in) operating activities
Amortization of identifiable intangible assets	2,039	1,831
Depreciation expense	4,219	3,792
Bad debt expense	(262)	211
Deferred tax benefit	(1,022)	(1,241)
Amortization of debt financing costs	85	93
Gain on sale of assets	(145)	(176)
Stock-based compensation expense	1,476	1,388
(Increase) decrease in-
Receivables, net	17,142	2,854
Inventories	(370)	(1,263)
Prepaid expenses and other current assets	(179)	735
Costs and estimated earnings in excess of billings	(1,837)	(3,592)
Other noncurrent assets	49	278
Increase (decrease) in-
Accounts payable and accrued liabilities	(9,316)	3,721
Billings in excess of costs and estimated earnings	(8,526)	4,817
Other long-term liabilities	(86)	78
Net cash provided by operating activities	13,022	20,415
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(3,765)	(3,623)
Proceeds from sales of property and equipment	220	206
Cash paid for acquisitions, net of cash acquired	(57,071)	(5,350)
Net cash used in investing activities	(60,616)	(8,767)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from revolving line of credit	132,000	14,500
Payments on revolving line of credit	(91,000)	(17,000)
Payments on other debt	(17)
Payments on capital lease obligations	(66)	(84)
Debt financing costs	(789)
Payments of dividends to shareholders	(2,426)	(2,237)
Share repurchase program	(2,840)
Shares received in lieu of tax withholding	(562)
Excess tax benefit of stock-based compensation	95	90
Proceeds from exercise of options	275	297
Distributions to noncontrolling interests		(41)
Payments for contingent consideration arrangements		(345)
Net cash provided by (used in) financing activities	34,670	(4,820)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(12,924)	6,828
CASH AND CASH EQUIVALENTS, beginning of period	56,464	32,064
CASH AND CASH EQUIVALENTS, end of period	$ 43,540	$ 38,892

Business and Organization

3 Months Ended

Mar. 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 41% of our consolidated 2016 revenue is attributable to installation of systems in newly constructed facilities, with the remaining 59% 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	$	289,456		75	%
Plumbing		54,032		14	%
Building Automation Control Systems		23,157		6	%
Other		19,297		5	%

Total	$	385,942		100	%

Summary of Significant Accounting Policies	3 Months Ended
Summary of Significant Accounting Policies	Mar. 31, 2016
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation These interim statements should be read in conjunction with the historical Consolidated Financial Statements and related notes of Comfort Systems included in the Annual Report on Form 10-K as filed with the Securities and Exchange Commission ("SEC") for the year ended December 31, 2015 (the "Form 10-K"). The accompanying unaudited consolidated financial statements were prepared using generally accepted accounting principles for interim financial information and the instructions to Form 10-Q and applicable rules of Regulation S-X of the SEC. Accordingly, these financial statements do not include all the footnotes required by generally accepted accounting principles for complete financial statements and should be read in conjunction with the Form 10-K. We believe all adjustments necessary for a fair presentation of these interim statements have been included and are of a normal and recurring nature. Certain amounts in prior periods may have been reclassified to conform to the current year presentation. The effects of the reclassifications were not material to the unaudited consolidated financial statements. The results of operations for interim periods are not necessarily indicative of the results for the full fiscal year. 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. Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board ("FASB") issued 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 at the date of initial application. We currently plan to use the modified retrospective basis on the adoption date. It is effective for annual periods beginning after December 15, 2017, including interim periods within that reporting period. We are currently evaluating the potential impact of this authoritative guidance 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 are currently evaluating the potential impact of this authoritative guidance on our consolidated financial statements. In February 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2016-02, "Leases (Topic 842)" ("ASU 2016-02"). 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 Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2016-09, "Compensation—Stock Compensation (Topic 718)" ("ASU 2016-09"). The standard will change certain aspects of accounting for share-based payments to employees. Specifically, the new guidance requires all income tax effects to be recognized in the income statement when the awards vest or are settled. It will also allow an employer to repurchase more of an employee's shares than it can today 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 are currently evaluating the potential impact of this authoritative guidance on our consolidated financial statements. 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. 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.

Fair Value Measurements

3 Months Ended

Mar. 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 March 31, 2016 (in thousands):

			Fair Value Measurements at Reporting Date Using
	Balance March 31, 2016		Quoted Prices In Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash and cash equivalents	$	43,540	$	43,540	$	—	$	—
Life insurance—cash surrender value	$	3,618	$	—	$	3,618	$	—
Contingent earn-out obligations	$	3,690	$	—	$	—	$	3,690

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 49 employees with a combined face value of $45.7 million. The policy is 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 $3.6 million as of March 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		—
Adjustments to fair value		—

Balance at end of period	$	3,690

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. We did not recognize any impairments, in the current quarter, 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	3 Months Ended
Acquisitions	Mar. 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 $47.0 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 preliminary 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 $14.5 million. The preliminary acquisition date fair value of consideration transferred for this acquisition was $19.5 million, of which $13.5 million was allocated to goodwill and identifiable intangible assets. The preliminary 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. Our consolidated balance sheet includes preliminary allocations of the purchase price to the assets acquired and liabilities assumed for this acquisition pending the completion of the final valuation of intangible assets and accrued liabilities. The acquisitions completed in the current year were not material, individually or in the aggregate. Other Acquisitions We funded cash of $0.8 million in the first quarter of 2016 for an acquisition completed in the fourth quarter of 2015. We also completed two acquisitions in the first quarter of 2015. These acquisitions were not material and were "tucked-in" with existing operations. The total purchase price for the "tucked-in" acquisitions, including earn-outs, was $6.7 million in the first quarter of 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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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+ Details

Goodwill

3 Months Ended

Mar. 31, 2016

Goodwill

Goodwill

5. Goodwill

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

	March 31, 2016		December 31, 2015
Balance at beginning of year	$	143,874	$	140,341
Additions		3,423		3,533

Balance at end of period	$	147,297	$	143,874

Debt Obligations

3 Months Ended

Mar. 31, 2016

Debt Obligations

Debt Obligations

6. Debt Obligations

Debt obligations consist of the following (in thousands):

	March 31, 2016			December 31, 2015
Revolving credit facility	$	51,000		$	10,000
Notes to former owners		2,750			1,000
Other debt		380			—
Capital lease obligations		441			507

Total debt		54,571			11,507
Less—current portion		(841	)		(751	)

Total long-term portion of debt	$	53,730		$	10,756

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. As of March 31, 2016, we had $51.0 million of outstanding borrowings, $41.5 million in letters of credit outstanding and $232.5 million of credit available.

There are two interest rate options for borrowings under the Facility, the Base Rate Loan Option and the Eurodollar Rate Loan Option. These rates are floating rates determined by the broad financial markets, meaning they can and do move up and down from time to time. Additional margins are then added to these two rates.

The following is a summary of the 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	%

The weighted average interest rate applicable to the borrowings under the Facility was approximately 1.7% as of March 31, 2016.

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 for a fee. 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 a claim is unlikely in the foreseeable future. The letter of credit fees range from 1.25% to 2.00% per annum, based on the ratio of Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA, as defined in the credit agreement.

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. These fees range from 0.20% to 0.35% per annum, based on the ratio of Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA, as defined in the credit agreement.

The Facility contains financial covenants defining various financial measures and the levels of these measures with which we must comply. Covenant compliance is assessed as of each quarter end.

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 March 31, 2016 was 0.4.

Fixed Charge Coverage Ratio—The Facility requires that the ratio of (a) Credit Facility Adjusted EBITDA, less non-financed capital expenditures, tax provision, dividends and amounts used to repurchase stock to (b) 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 March 31, 2016 was 30.4.

Other Restrictions—The Facility permits acquisitions of up to $30.0 million per transaction, provided that the aggregate purchase price of all such acquisitions in the same fiscal year does not exceed $65.0 million. However, these limitations only apply when the Company's Total Leverage Ratio is 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 March 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 $2.8 million as of March 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 March 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 acquisition in the fourth quarter of 2014, we issued a subordinated note to the former owners with an outstanding balance of $1.0 million as of March 31, 2016 that bears interest, payable quarterly, at a weighted average interest rate of 2.5%. The principal is due in equal installments in October 2016 and 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 March 31, 2016, $0.4 million of the note was outstanding, of which $0.1 million was considered current.

In addition, with one of our acquisitions we acquired capital lease obligations. As of March 31, 2016, $0.4 million of capital lease obligations were outstanding, of which $0.2 million was considered current.

Commitments and Contingencies	3 Months Ended
Commitments and Contingencies	Mar. 31, 2016
Commitments and Contingencies
Commitments and Contingencies	7. Commitments and Contingencies Claims and Lawsuits We are subject to certain legal and regulatory claims, including lawsuits arising in the normal course of business. We maintain various insurance coverages to minimize financial risk associated with these claims. We have estimated and provided accruals for probable losses and related legal fees associated with certain litigation in the accompanying consolidated financial statements. While we cannot predict the outcome of these proceedings, in management's opinion and based on reports of counsel, any liability arising from these matters individually and in the aggregate will not have a material effect on our operating results, cash flows or financial condition, after giving effect to provisions already recorded. 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 have seen some strengthening as the commercial construction markets have started to rebound. Bonding capacity remains 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 up to deductible amounts are estimated and accrued based upon known facts, historical trends and industry averages. 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.

Stockholders' Equity

3 Months Ended

Mar. 31, 2016

Stockholders' Equity

Stockholders' Equity

8. Stockholders' Equity

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, contingently issuable 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 three months ended March 31, 2016 and for the three months ended March 31, 2015.

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):

	Three Months Ended March 31,
	2016			2015
Common shares outstanding, end of period		37,392			37,307
Effect of using weighted average common shares outstanding		(48	)		(26	)

Shares used in computing earnings per share—basic		37,344			37,281
Effect of shares issuable under stock option plans based on the treasury stock method		241			233
Effect of contingently issuable restricted shares		145			91

Shares used in computing earnings per share—diluted		37,730			37,605

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. Since the inception of the repurchase program, the Board has approved 7.6 million shares to be repurchased. As of March 31, 2016, we have repurchased a cumulative total of 7.0 million shares at an average price of $12.22 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 current quarter, we repurchased 0.1 million shares for approximately $2.8 million at an average price of $27.84 per share.

Summary of Significant Accounting Policies (Policies)	3 Months Ended
Summary of Significant Accounting Policies (Policies)	Mar. 31, 2016
Summary of Significant Accounting Policies
Basis of Presentation	Basis of Presentation These interim statements should be read in conjunction with the historical Consolidated Financial Statements and related notes of Comfort Systems included in the Annual Report on Form 10-K as filed with the Securities and Exchange Commission ("SEC") for the year ended December 31, 2015 (the "Form 10-K"). The accompanying unaudited consolidated financial statements were prepared using generally accepted accounting principles for interim financial information and the instructions to Form 10-Q and applicable rules of Regulation S-X of the SEC. Accordingly, these financial statements do not include all the footnotes required by generally accepted accounting principles for complete financial statements and should be read in conjunction with the Form 10-K. We believe all adjustments necessary for a fair presentation of these interim statements have been included and are of a normal and recurring nature. Certain amounts in prior periods may have been reclassified to conform to the current year presentation. The effects of the reclassifications were not material to the unaudited consolidated financial statements. The results of operations for interim periods are not necessarily indicative of the results for the full fiscal year.
Use of Estimates	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.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board ("FASB") issued 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 at the date of initial application. We currently plan to use the modified retrospective basis on the adoption date. It is effective for annual periods beginning after December 15, 2017, including interim periods within that reporting period. We are currently evaluating the potential impact of this authoritative guidance 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 are currently evaluating the potential impact of this authoritative guidance on our consolidated financial statements. In February 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2016-02, "Leases (Topic 842)" ("ASU 2016-02"). 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 Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2016-09, "Compensation—Stock Compensation (Topic 718)" ("ASU 2016-09"). The standard will change certain aspects of accounting for share-based payments to employees. Specifically, the new guidance requires all income tax effects to be recognized in the income statement when the awards vest or are settled. It will also allow an employer to repurchase more of an employee's shares than it can today 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 are currently evaluating the potential impact of this authoritative guidance on our consolidated financial statements.
Financial Instruments	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.
Segment Disclosure	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.

Business and Organization (Tables)

3 Months Ended

Mar. 31, 2016

Business and Organization

Schedule of service activities

	Revenue
Service Activity	$ in thousands		%
HVAC	$	289,456		75	%
Plumbing		54,032		14	%
Building Automation Control Systems		23,157		6	%
Other		19,297		5	%

Total	$	385,942		100	%

Fair Value Measurements (Tables)

3 Months Ended

Mar. 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

			Fair Value Measurements at Reporting Date Using
	Balance March 31, 2016		Quoted Prices In Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash and cash equivalents	$	43,540	$	43,540	$	—	$	—
Life insurance—cash surrender value	$	3,618	$	—	$	3,618	$	—
Contingent earn-out obligations	$	3,690	$	—	$	—	$	3,690

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		—
Adjustments to fair value		—

Balance at end of period	$	3,690

Goodwill (Tables)

3 Months Ended

Mar. 31, 2016

Goodwill

Schedule of changes in the carrying amount of goodwill

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

	March 31, 2016		December 31, 2015
Balance at beginning of year	$	143,874	$	140,341
Additions		3,423		3,533

Balance at end of period	$	147,297	$	143,874

Debt Obligations (Tables)

3 Months Ended

Mar. 31, 2016

Debt Obligations

Schedule of components of debt obligations

Debt obligations consist of the following (in thousands):

	March 31, 2016			December 31, 2015
Revolving credit facility	$	51,000		$	10,000
Notes to former owners		2,750			1,000
Other debt		380			—
Capital lease obligations		441			507

Total debt		54,571			11,507
Less—current portion		(841	)		(751	)

Total long-term portion of debt	$	53,730		$	10,756

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	%

Stockholders' Equity (Tables)

3 Months Ended

Mar. 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):

	Three Months Ended March 31,
	2016			2015
Common shares outstanding, end of period		37,392			37,307
Effect of using weighted average common shares outstanding		(48	)		(26	)

Shares used in computing earnings per share—basic		37,344			37,281
Effect of shares issuable under stock option plans based on the treasury stock method		241			233
Effect of contingently issuable restricted shares		145			91

Shares used in computing earnings per share—diluted		37,730			37,605

Business and Organization (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Business and Organization
Revenue	$ 385,942	$ 369,547
Percentage of revenue attributable to services	100.00%
Installation of systems in newly constructed facilities
Business and Organization
Percentage of revenue attributable to services	41.00%
Maintenance, repair and replacement services
Business and Organization
Percentage of revenue attributable to services	59.00%
HVAC
Business and Organization
Revenue	$ 289,456
Percentage of revenue attributable to services	75.00%
Plumbing
Business and Organization
Revenue	$ 54,032
Percentage of revenue attributable to services	14.00%
Building Automation Control Systems
Business and Organization
Revenue	$ 23,157
Percentage of revenue attributable to services	6.00%
Other
Business and Organization
Revenue	$ 19,297
Percentage of revenue attributable to services	5.00%

Fair Value Measurements (Details) $ in Thousands	3 Months Ended
Fair Value Measurements (Details) $ in Thousands	Mar. 31, 2016 USD ($) item	Dec. 31, 2015 USD ($)
Fair Value Measurements
Number of employees covered under life insurance policies \| item	49
Combined face value of life insurance policies	$ 45,700
Cash surrender value	3,600	$ 3,600
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
Balance at end of period	3,690
Recurring basis \| Total
Fair Value Measurements
Cash and cash equivalents	43,540
Life insurance - cash surrender value	3,618
Contingent earn-out obligations	3,690
Recurring basis \| Quoted Market Prices In Active Markets for Identical Assets (Level 1)
Fair Value Measurements
Cash and cash equivalents	43,540
Recurring basis \| Fair Value Measurements at Reporting Date Using Significant Other Observable Inputs (Level 2)
Fair Value Measurements
Life insurance - cash surrender value	3,618
Recurring basis \| Significant Unobservable Inputs (Level 3)
Fair Value Measurements
Contingent earn-out obligations	$ 3,690

Acquisitions (Details) $ in Millions		3 Months Ended		12 Months Ended
Acquisitions (Details) $ in Millions	Jan. 01, 2016 USD ($)	Mar. 31, 2016 USD ($) item	Mar. 31, 2015 USD ($) item	Dec. 31, 2015 USD ($)
Acquisitions
Number of acquisitions \| item		2
Environmental Air Systems
Acquisitions
Total purchase price	$ 47.0
Interest acquired (as a percent)	40.00%
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets
Purchase price paid in cash	$ 42.0
Shoffner
Acquisitions
Total purchase price		$ 19.5
Interest acquired (as a percent)		100.00%
Amount allocated to goodwill and identifiable intangible assets for acquisitions		$ 13.5
Revenue in consolidated results		14.5
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets
Purchase price paid in cash		$ 15.5
Other Acquisitions
Acquisitions
Total purchase price				$ 6.7
Number of acquisitions \| item			2
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets
Cash and cash equivalents			$ 0.8

Goodwill (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Goodwill (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Changes in the carrying amount of goodwill
Balance at the beginning of year	$ 143,874	$ 140,341
Additions	3,423	3,533
Balance at end of period	$ 147,297	$ 143,874

Debt Obligations (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Long-Term Debt Obligations
Total debt	$ 54,571	$ 11,507
Less - current portion	(841)	(751)
Total long-term portion of debt	53,730	10,756
Revolving credit facility
Long-Term Debt Obligations
Total debt	51,000	10,000
Notes to former owners
Long-Term Debt Obligations
Total debt	2,750	1,000
Other debt
Long-Term Debt Obligations
Total debt	380
Capital lease obligations
Long-Term Debt Obligations
Total debt	$ 441	$ 507

Debt Obligations-Other (Details) $ in Thousands		3 Months Ended		12 Months Ended
Debt Obligations-Other (Details) $ in Thousands	Feb. 22, 2016 USD ($)	Mar. 31, 2016 USD ($) item	Mar. 31, 2015 USD ($) item	Dec. 31, 2015 USD ($)	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		$ 9,755	$ 6,889	$ 57,440
Income taxes-continuing operations		$ (5,497)	$ (3,793)
Principal financial covenants
Leverage ratio		3.00
Other disclosures
Current portion of capital lease obligations		$ 241		$ 251
Number of acquisitions \| item		2
Shoffner
Other disclosures
Debt acquired related to coil line duct processing system		$ 400
Outstanding balance		400
Current debt		$ 100
Other Acquisitions
Other disclosures
Number of acquisitions \| item			2
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
Letters of credit amount outstanding		$ 41,500
Credit available		$ 232,500
Principal financial covenants
Leverage ratio		0.40
Number of quarters of capital expenditures, tax provision, dividends and stock repurchase payments used for calculation of fixed charge coverage ratio \| item		4
Fixed charge coverage ratio		30.40
Number of interest rate options \| item		2
Other disclosures
Weighted average interest rate (as a percent)		1.70%
Revolving credit facility \| Through maturity
Principal financial covenants
Leverage ratio		2.75
Revolving credit facility \| Minimum
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 \| Maximum
Principal financial covenants
Amount of stock repurchases to maintain maximum net leverage ratio		$ 25,000
Net leverage ratio after giving effect to stock repurchases for calculation of the fixed charge coverage ratio		1.50
Permitted amount of acquisitions per transaction		$ 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
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 \| 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
Outstanding balance		$ 2,800
Notes to former owners \| Shoffner
Long-Term Debt Obligations
Outstanding borrowings		$ 1,800
Other disclosures
Weighted average interest rate (as a percent)		3.00%
Notes to former owners \| Other Acquisitions
Long-Term Debt Obligations
Outstanding borrowings		$ 1,000
Other disclosures
Weighted average interest rate (as a percent)		2.50%
Other debt \| Dyna Ten
Other disclosures
Capital lease obligation pertaining to acquisition		$ 400
Current portion of capital lease obligations		$ 200

Commitments and Contingencies (Details) - Surety	3 Months Ended
Commitments and Contingencies (Details) - Surety	Mar. 31, 2016
Minimum
Surety
Percentage of business which has required bonds	20.00%
Maximum
Surety
Percentage of business which has required bonds	30.00%

Stockholders' Equity (Details) - shares shares in Millions	3 Months Ended
Stockholders' Equity (Details) - shares shares in Millions	Mar. 31, 2016	Mar. 31, 2015
Stock Options
Earnings Per Share
Anti-dilutive securities excluded from computation of earnings per share amount (in shares)	0.1	0.1

Stockholders' Equity-Number of Shares (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
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	37,392	37,307
Effect of using weighted average common shares outstanding	(48)	(26)
Shares used in computing earnings per share - basic	37,344	37,281
Effect of shares issuable under stock option plans based on the treasury stock method	241	233
Effect of contingently issuable restricted shares	145	91
Shares used in computing earnings per share - diluted	37,730	37,605

Stockholders' Equity- Incentive and Other (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended	108 Months Ended
	Mar. 31, 2016	Mar. 31, 2016	Mar. 29, 2007
Share Repurchase Program
Number of shares of outstanding common stock authorized to be acquired under a stock repurchase program	7.6	7.6	1.0
Share repurchase (in shares)		7.0
Average price (in dollars per share)	$ 27.84	$ 12.22
Repurchased carrying basis	$ 2.8	$ 2.8
Maximum
Share Repurchase Program
Share repurchase (in shares)	0.1