Comfort Systems USA (FIX) 10-Q 26 Apr 23 2023 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2023	Apr. 21, 2023
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2023
Document Transition Report	false
Entity File Number	1-13011
Entity Registrant Name	COMFORT SYSTEMS USA, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	76-0526487
Entity Address, Address Line One	675 Bering Drive
Entity Address, Address Line Two	Suite 400
Entity Address, City or Town	Houston
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77057
City Area Code	713
Local Phone Number	830-9600
Title of 12(b) Security	Common Stock, $0.01 par value
Trading Symbol	FIX
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		35,767,519
Entity Central Index Key	0001035983
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--12-31
Amendment Flag	false

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
CURRENT ASSETS:
Cash and cash equivalents	$ 48,560	$ 57,214
Billed accounts receivable, less allowance for credit losses of $9,718 and $10,640, respectively	1,176,378	1,024,082
Unbilled accounts receivable, less allowance for credit losses of $1,031 and $1,011, respectively	81,151	77,030
Other receivables, less allowance for credit losses of $518 and $510, respectively	41,912	38,369
Inventories	37,013	35,309
Prepaid expenses and other	47,190	48,456
Costs and estimated earnings in excess of billings, less allowance for credit losses of $52 and $80, respectively	26,820	27,211
Total current assets	1,459,024	1,307,671
PROPERTY AND EQUIPMENT, NET	155,021	143,949
LEASE RIGHT-OF-USE ASSET	134,755	130,666
GOODWILL	637,434	611,789
IDENTIFIABLE INTANGIBLE ASSETS, NET	296,070	273,901
DEFERRED TAX ASSETS	143,202	115,665
OTHER NONCURRENT ASSETS	13,965	13,837
Total assets	2,839,471	2,597,478
CURRENT LIABILITIES:
Current maturities of long-term debt	11,468	9,000
Accounts payable	351,509	337,385
Accrued compensation and benefits	115,606	127,765
Billings in excess of costs and estimated earnings and deferred revenue	717,294	548,293
Accrued self-insurance	23,865	27,644
Other current liabilities	186,917	120,715
Total current liabilities	1,406,659	1,170,802
LONG-TERM DEBT	197,761	247,245
LEASE LIABILITIES	115,018	111,744
OTHER LONG-TERM LIABILITIES	66,543	67,764
Total liabilities	1,785,981	1,597,555
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, 5,371,392 and 5,362,224 shares, respectively	(191,411)	(187,212)
Additional paid-in capital	338,884	332,080
Retained earnings	905,606	854,644
Total stockholders' equity	1,053,490	999,923
Total liabilities and stockholders' equity	$ 2,839,471	$ 2,597,478

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
CONSOLIDATED BALANCE SHEETS
Billed accounts receivable, allowance for credit losses (in dollars)	$ 9,718	$ 10,640
Unbilled accounts receivable, allowance for credit losses (in dollars)	1,031	1,011
Other receivables, allowance for credit losses (in dollars)	518	510
Costs and estimated earnings in excess of billings, allowance for credit losses (in dollars)	$ 52	$ 80
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	5,371,392	5,362,224

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
CONSOLIDATED STATEMENTS OF OPERATIONS
REVENUE	$ 1,174,640	$ 885,216
COST OF SERVICES	969,235	732,072
Gross profit	205,405	153,144
SELLING, GENERAL AND ADMINISTRATIVE EXPENSES	135,032	117,776
GAIN ON SALE OF ASSETS	(512)	(323)
Operating income	70,885	35,691
OTHER INCOME (EXPENSE):
Interest income	1,397	3
Interest expense	(4,076)	(2,129)
Changes in the fair value of contingent earn-out obligations	(2,382)	4,088
Other	1	56
Other income (expense)	(5,060)	2,018
INCOME BEFORE INCOME TAXES	65,825	37,709
PROVISION (BENEFIT) FOR INCOME TAXES	8,609	(49,053)
NET INCOME	$ 57,216	$ 86,762
INCOME PER SHARE:
Basic	$ 1.60	$ 2.40
Diluted	$ 1.59	$ 2.40
SHARES USED IN COMPUTING INCOME PER SHARE:
Basic	35,812	36,076
Diluted	35,907	36,188

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Treasury Stock	Additional Paid-In Capital	Retained Earnings	Total
BALANCE at Dec. 31, 2021	$ 411	$ (150,580)	$ 327,061	$ 628,774	$ 805,666
BALANCE (in shares) at Dec. 31, 2021	41,123,365
BALANCE (in shares) at Dec. 31, 2021		(5,032,311)
Increase (Decrease) in Stockholders' Equity
Net income				86,762	86,762
Issuance of Stock:
Issuance of restricted stock & performance stock		$ 1,232	2,312		3,544
Issuance of restricted stock & performance stock (in shares)		38,863
Shares received in lieu of tax withholding on vested restricted stock		$ (1,399)			(1,399)
Shares received in lieu of tax withholding on vested restricted stock (in shares)		(15,348)
Stock-based compensation			2,605		2,605
Dividends				(4,673)	(4,673)
Share repurchase		$ (14,097)			(14,097)
Share repurchase (in shares)		(161,614)
BALANCE at Mar. 31, 2022	$ 411	$ (164,844)	331,978	710,863	878,408
BALANCE (in shares) at Mar. 31, 2022	41,123,365
BALANCE (in shares) at Mar. 31, 2022		(5,170,410)
BALANCE at Dec. 31, 2022	$ 411	$ (187,212)	332,080	854,644	$ 999,923
BALANCE (in shares) at Dec. 31, 2022	41,123,365				41,123,365
BALANCE (in shares) at Dec. 31, 2022		(5,362,224)			5,362,224
Increase (Decrease) in Stockholders' Equity
Net income				57,216	$ 57,216
Issuance of Stock:
Issuance of shares for options exercised		$ 36	(18)		18
Issuance of shares for options exercised (in shares)		1,000
Issuance of restricted stock & performance stock		$ 1,131	3,384		4,515
Issuance of restricted stock & performance stock (in shares)		31,960
Shares received in lieu of tax withholding on vested restricted stock		$ (1,798)			(1,798)
Shares received in lieu of tax withholding on vested restricted stock (in shares)		(12,728)
Stock-based compensation			3,438		3,438
Dividends				(6,254)	(6,254)
Share repurchase		$ (3,568)			(3,568)
Share repurchase (in shares)		(29,400)
BALANCE at Mar. 31, 2023	$ 411	$ (191,411)	$ 338,884	$ 905,606	$ 1,053,490
BALANCE (in shares) at Mar. 31, 2023	41,123,365				41,123,365
BALANCE (in shares) at Mar. 31, 2023		(5,371,392)			5,371,392

CONSOLIDATED STATEMENTS OF ST_2

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY
Dividends (per share)	$ 0.175	$ 0.13

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 57,216	$ 86,762
Adjustments to reconcile net income to net cash provided by operating activities-
Amortization of identifiable intangible assets	10,331	12,791
Depreciation expense	9,187	8,046
Change in right-of-use assets	5,357	4,734
Bad debt expense	946	25
Deferred tax provision (benefit)	(27,537)	2,328
Amortization of debt financing costs	169	133
Gain on sale of assets	(512)	(323)
Changes in the fair value of contingent earn-out obligations	2,382	(4,088)
Stock-based compensation	6,141	3,996
(Increase) decrease in-
Receivables, net	(125,937)	(52,701)
Inventories	(1,386)	(3,104)
Prepaid expenses and other current assets	(911)	(2,803)
Costs and estimated earnings in excess of billings and unbilled accounts receivable	(2,281)	2,562
Other noncurrent assets	(298)	181
Increase (decrease) in-
Accounts payable and accrued liabilities	28,652	3,544
Billings in excess of costs and estimated earnings and deferred revenue	159,140	7,401
Other long-term liabilities	6,250	(5,755)
Net cash provided by operating activities	126,909	63,729
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(16,520)	(9,192)
Proceeds from sales of property and equipment	622	1,056
Cash paid for acquisitions, net of cash acquired	(53,047)	3
Payments for investments		(1,236)
Net cash used in investing activities	(68,945)	(9,369)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from revolving credit facility	85,000	50,000
Payments on revolving credit facility	(140,000)	(10,000)
Payments on term loan		(7,500)
Payments on other debt	(16)	(7,797)
Payments on finance lease liabilities		(253)
Payments of dividends to stockholders	(6,254)	(4,673)
Share repurchase	(3,568)	(14,097)
Shares received in lieu of tax withholding	(1,798)	(1,399)
Proceeds from exercise of options	18
Deferred acquisition payments		(50)
Payments for contingent consideration arrangements		(1,752)
Net cash provided by (used in) financing activities	(66,618)	2,479
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(8,654)	56,839
CASH AND CASH EQUIVALENTS, beginning of period	57,214	58,776
CASH AND CASH EQUIVALENTS, end of period	$ 48,560	$ 115,615

Business and Organization

Business and Organization	3 Months Ended
	Mar. 31, 2023
Business and Organization
Business and Organization	1. Business and Organization ​ Comfort Systems USA, Inc., a Delaware corporation, provides comprehensive mechanical and electrical contracting services, which principally includes heating, ventilation and air conditioning (“HVAC”), plumbing, electrical, piping and controls, as well as off-site construction, monitoring and fire protection. We build, install, maintain, repair and replace mechanical, electrical and plumbing (“MEP”) systems throughout the United States. The terms “Comfort Systems,” “we,” “us,” or the “Company,” refer to Comfort Systems USA, Inc. or Comfort Systems USA, Inc. and its consolidated subsidiaries, as appropriate in the context. ​

Summary of Significant Accounti

Summary of Significant Accounting Policies and Estimates	3 Months Ended
	Mar. 31, 2023
Summary of Significant Accounting Policies and Estimates
Summary of Significant Accounting Policies and Estimates	2. Summary of Significant Accounting Policies and Estimates ​ 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, 2022 (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. The results of operations for interim periods are not necessarily indicative of the results for the full fiscal year. Certain amounts in prior periods have been reclassified to conform to the current period presentation. The effects of the reclassifications were not material to the consolidated financial statements. ​ Use of Estimates ​ The preparation of financial statements in conformity with generally accepted accounting principles requires the use of estimates and assumptions by management in determining the reported amounts of assets and liabilities, revenue and expenses and disclosures regarding contingent assets and liabilities. Actual results could differ from those estimates. The most significant estimates used in our financial statements affect revenue and cost recognition for construction contracts, self-insurance accruals, accounting for income taxes, fair value accounting for acquisitions and the quantification of fair value for reporting units in connection with our goodwill impairment testing. ​ Recent Accounting Pronouncements ​ Recently Adopted Accounting Pronouncements ​ In October 2021, the FASB issued ASU 2021-08, “Business Combinations (Topic 805): Accounting for Contract Assets and Contract Liabilities from Contracts with Customers.” This standard requires an acquirer to apply Accounting Standards Codification Topic 606 to recognize and measure contract assets and contract liabilities in a business combination. ASU 2021-08 is effective for fiscal years beginning after December 15, 2022 and interim periods within that year. We adopted this standard on January 1, 2023, and the impact was not material on our consolidated financial statements. ​ Revenue Recognition ​ We recognize revenue over time for all of our services as we perform them because (i) control continuously transfers to that customer as work progresses, and (ii) we have the right to bill the customer as costs are incurred. The customer typically controls the work in process, as evidenced either by contractual termination clauses or by our rights to payment for work performed to date, plus a reasonable profit, for delivery of products or services that do not have an alternative use to the Company. ​ For the reasons listed above, revenue is recognized based on the extent of progress towards completion of the performance obligation. The selection of the method to measure progress towards completion requires judgment and is based on the nature of the products or services to be provided. We generally use a cost-to-cost input method to measure our progress towards satisfaction of the performance obligation for our contracts, as it best depicts the transfer of assets to the customer that occurs as we incur costs on our contracts. Under the cost-to-cost input method, the extent of progress towards completion is measured based on the ratio of costs incurred to date to the total estimated costs at completion of the performance obligation. Revenue, including estimated fees or profits, is recorded proportionally as costs are incurred. Costs to fulfill include labor, materials, subcontractors’ costs, other direct costs and an allocation of indirect costs. ​ For a small portion of our business in which our services are delivered in the form of service maintenance agreements for existing systems to be repaired and maintained, as opposed to constructed, our performance obligation is to maintain the customer’s mechanical system for a specific period of time. Similar to construction jobs, we recognize revenue over time; however, for service maintenance agreements in which the full cost to provide services may not be known, we generally use an input method to recognize revenue, which is based on the amount of time we have provided our services out of the total time we have been contracted to perform those services. Our revenue recognition policy is further discussed in Note 3 “Revenue from Contracts with Customers.” ​ Accounts Receivable and Allowance for Credit Losses ​ We are required to estimate and record the expected credit losses over the contractual life of our financial assets measured at amortized cost, including billed and unbilled accounts receivable, other receivables and contract assets. Accounts receivable include amounts from work completed in which we have billed or have an unconditional right to bill our customers. Our trade receivables are contractually due in less than a year. ​ We estimate our credit losses using a loss-rate method for each of our identified portfolio segments. Our portfolio segments are construction, service and other. While our construction and service financial assets are often with the same subset of customers and industries, our construction financial assets will generally have a lower loss-rate than service financial assets due to lien rights, which we are more likely to have on construction jobs. These lien rights result in lower credit loss expenses on average compared to receivables that do not have lien rights. Financial assets classified as Other include receivables that are not related to our core revenue producing activities, such as receivables related to our acquisition activity from former owners, our vendor rebate program or receivables for estimated losses in excess of our insurance deductible, which are accrued with a corresponding accrued insurance liability. ​ Loss rates for our portfolios are based on numerous factors, including our history of credit loss expense by portfolio, the financial strength of our customers and counterparties in each portfolio, the aging of our receivables, our expectation of likelihood of payment, macroeconomic trends in the U.S. and the current and forecasted nonresidential construction market trends in the U.S. ​ In addition to the loss-rate calculations discussed above, we also record allowance for credit losses for specific receivables that are deemed to have a higher risk profile than the rest of the respective pool of receivables (e.g., when we hold concerns about a specific customer going bankrupt and no longer being able to pay the receivables due to us). ​ Income Taxes ​ We conduct business throughout the United States in virtually all fifty states. Our effective tax rate changes based upon our relative profitability, or lack thereof, in the federal and various state jurisdictions with differing tax rates and rules. In addition, discrete items such as tax law changes, judgments and legal structures, can impact our effective tax rate. These items can also include the tax treatment for impairment of goodwill and other intangible assets, changes in fair value of acquisition-related assets and liabilities, uncertain tax positions, and accounting for losses associated with underperforming operations. ​ Following an Internal Revenue Service survey of previously filed refund claims for the 2016, 2017 and 2018 tax years, the Joint Committee on Taxation approved such refunds in late January 2022. As a result, our benefit for income taxes in the first quarter of 2022 included a $28.8 million reduction in unrecognized tax benefits plus approximately $1.6 million of net interest income on the refunds. ​ Our benefit for income taxes in the first quarter of 2022 was further increased by $26.8 million for the expected refunds due to our intention to claim the R&D tax credit for the 2019, 2020 and 2021 tax years. In the third quarter of 2022, we claimed the R&D tax credit on our originally filed 2021 federal return and recognized an additional $1.7 million benefit for the 2019, 2020 and 2021 tax years. Additionally, in February 2023, we filed amended federal returns for 2019 and 2020 requesting refunds primarily from claiming the R&D tax credit. ​ The Inflation Reduction Act was enacted on August 16, 2022. This law, among other provisions, provides a corporate alternative minimum tax on adjusted financial statement income over $1 billion, which is effective for tax years beginning after December 31, 2022, and a 1% excise tax on net corporate stock repurchases after December 31, 2022. The impact of the excise tax is recorded in “Treasury Stock” within our Consolidated Balance Sheet. We currently believe these provisions will be immaterial to our overall financial results, financial position and cash flows. ​ Financial Instruments ​ Our financial instruments consist of cash and cash equivalents, accounts receivable, other receivables, accounts payable and life insurance policies, for which we deem the carrying values approximate their fair value due to the short-term nature of these instruments, as well as notes to former owners and a revolving credit facility. Unbilled Accounts Receivable ​ Unbilled Accounts Receivable are amounts due to us that we have earned under a contract where our right to payment is unconditional. A right to consideration is unconditional if only the passage of time is required before payment of the consideration is due. ​ Investments ​ We have a $2.5 million investment with a fair value that is not readily determinable and is recorded at cost. This investment is included in “Other Noncurrent Assets” in our Consolidated Balance Sheet and is reviewed quarterly for impairment. We did not recognize any impairments in the current year related to this investment.

Revenue from Contracts with Cus

Revenue from Contracts with Customers	3 Months Ended
	Mar. 31, 2023
Revenue from Contracts with Customers
Revenue from Contracts with Customers	3. Revenue from Contracts with Customers ​ Revenue is recognized when control of the promised goods or services is transferred to our customers, in an amount that reflects the consideration to which we expect to be entitled in exchange for those goods or services. Sales-based taxes are excluded from revenue. ​ We provide mechanical and electrical contracting services. Our mechanical segment principally includes HVAC, plumbing, piping and controls, as well as off- site construction, monitoring and fire protection. Our electrical segment includes installation and servicing of electrical systems. We build, install, maintain, repair and replace products and systems throughout the United States. All of our revenue is recognized over time as we deliver goods and services to our customers. Revenue can be earned based on an agreed-upon fixed price or based on actual costs incurred, marked up at an agreed-upon percentage. ​ We account for a contract when: (i) it has approval and commitment from both parties, (ii) the rights of the parties are identified, (iii) payment terms are identified, (iv) the contract has commercial substance, and (v) collectability of consideration is probable. We consider the start of a project to be when the above criteria have been met and we either have written authorization from the customer to proceed or an executed contract. ​ We generally do not incur significant incremental costs related to obtaining or fulfilling a contract prior to the start of a project. On rare occasions, when significant pre-contract costs are incurred, they are capitalized and amortized over the life of the contract using a cost-to-cost input method to measure progress towards contract completion. We do not currently have any capitalized obtainment or fulfillment costs in our Consolidated Balance Sheet and have not incurred any impairment loss on such costs in the current year. ​ Due to the nature of the work required to be performed on many of our performance obligations, the estimation of total revenue and cost at completion (the process described below in more detail) is complex, subject to many variables and requires significant judgment. The consideration to which we are entitled on our long-term contracts may include both fixed and variable amounts. Variable amounts can either increase or decrease the transaction price. A common example of variable amounts that can either increase or decrease contract value are pending change orders that represent contract modifications for which a change in scope has been authorized or acknowledged by our customer, but the final adjustment to contract price is yet to be negotiated. Other examples of positive variable revenue include amounts awarded upon achievement of certain performance metrics, program milestones or cost of completion date targets and can be based upon customer discretion. Variable amounts can result in a deduction from contract revenue if we fail to meet stated performance requirements, such as complying with the construction schedule. ​ We include estimated amounts of variable consideration in the contract price to the extent it is probable that a significant reversal of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is resolved. Our estimates of variable consideration and determination of whether to include estimated amounts in the contract price are based largely on an assessment of our anticipated performance and all information (historical, current and forecasted) that is reasonably available to us. We reassess the amount of variable consideration each accounting period until the uncertainty associated with the variable consideration is resolved. Changes in the assessed amount of variable consideration are accounted for prospectively as a cumulative adjustment to revenue recognized in the current period. ​ Contracts are often modified to account for changes in contract specifications and requirements. We consider contract modifications to exist when the modification either creates new, or changes the existing, enforceable rights and obligations. Most of our contract modifications are for goods or services that are not distinct from the existing performance obligation(s). The effect of a contract modification on the transaction price, and our measure of progress for the performance obligation to which it relates, is recognized as an adjustment to revenue (either as an increase or decrease) on a cumulative catch-up basis. ​ We have a Company-wide policy requiring periodic review of the Estimate at Completion in which management reviews the progress and execution of our performance obligations and estimated remaining obligations. As part of this process, management reviews information including, but not limited to, any outstanding key contract matters, progress towards completion and the related program schedule, identified risks and opportunities and the related changes in estimates of revenue and costs. The risks and opportunities include management's judgment about the ability and cost to achieve the schedule (e.g., the number and type of milestone events), technical requirements (e.g., a newly developed product versus a mature product) and other contract requirements. Management must make assumptions and estimates regarding labor productivity and availability, the complexity of the work to be performed, the availability of materials, the length of time to complete the performance obligation (e.g., to estimate increases in wages and prices for materials and related support cost allocations), execution by our subcontractors, the availability and timing of funding from our customer, and overhead cost rates, among other variables. ​ Based on this analysis, any adjustments to revenue, cost of services, and the related impact to operating income are recognized as necessary in the quarter when they become known. These adjustments may result from positive program performance if we determine we will be successful in mitigating risks surrounding the technical, schedule and cost aspects of those performance obligations or realizing related opportunities and may result in an increase in operating income during the performance of individual performance obligations. Likewise, if we determine we will not be successful in mitigating these risks or realizing related opportunities, these adjustments may result in a decrease in operating income. Changes in estimates of revenue, cost of services and the related impact to operating income are recognized quarterly on a cumulative catch-up basis, meaning we recognize in the current period the cumulative effect of the changes on current and prior periods based on our progress towards complete satisfaction of a performance obligation ​ In the first three months of 2023 and 2022, net revenue recognized from our performance obligations satisfied in previous periods was not material. ​ Disaggregation of Revenue ​ Our consolidated 2023 revenue was derived from contracts to provide service activities in the mechanical and electrical services segments we serve. Refer to Note 11 “Segment Information” for additional information on our reportable segments. We disaggregate our revenue from contracts with customers by activity, customer type and service provided, as we believe it best depicts how the nature, amount, timing and uncertainty of our revenue and cash flows are affected by economic factors. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ ​ Revenue by Service Provided 2023 ​ 2022 ​ Mechanical Services ​ $ 918,615 78.2 % ​ $ 682,511 77.1 % ​ Electrical Services ​ ​ 256,025 ​ 21.8 % ​ ​ 202,705 ​ 22.9 % ​ Total ​ $ 1,174,640 ​ 100.0 % ​ $ 885,216 ​ 100.0 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ ​ Revenue by Type of Customer ​ 2023 ​ ​ 2022 ​ Manufacturing ​ $ 366,356 ​ 31.2 % ​ $ 314,729 ​ 35.5 % ​ Technology ​ ​ 226,249 ​ 19.3 % ​ ​ 95,455 ​ 10.8 % ​ Healthcare ​ ​ 159,815 ​ 13.5 % ​ ​ 134,795 ​ 15.2 % ​ Education ​ ​ 110,253 ​ 9.4 % ​ ​ 89,446 ​ 10.1 % ​ Office Buildings ​ ​ 98,195 ​ 8.4 % ​ ​ 75,115 ​ 8.5 % ​ Retail, Restaurants and Entertainment ​ ​ 76,194 ​ 6.5 % ​ ​ 65,582 ​ 7.4 % ​ Government ​ ​ 64,415 ​ 5.5 % ​ ​ 57,465 ​ 6.5 % ​ Multi-Family and Residential ​ ​ 45,007 ​ 3.8 % ​ ​ 24,442 ​ 2.8 % ​ Other ​ ​ 28,156 ​ 2.4 % ​ ​ 28,187 ​ 3.2 % ​ Total ​ $ 1,174,640 ​ 100.0 % ​ $ 885,216 ​ 100.0 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ ​ Revenue by Activity Type ​ 2023 ​ ​ 2022 ​ New Construction ​ $ 627,952 ​ 53.5 % ​ $ 429,418 ​ 48.5 % ​ Existing Building Construction ​ ​ 309,483 ​ 26.3 % ​ ​ 259,285 ​ 29.3 % ​ Service Projects ​ ​ 103,105 ​ 8.8 % ​ ​ 76,252 ​ 8.6 % ​ Service Calls, Maintenance and Monitoring ​ ​ 134,100 ​ 11.4 % ​ ​ 120,261 ​ 13.6 % ​ Total ​ $ 1,174,640 ​ 100.0 % ​ $ 885,216 ​ 100.0 % ​ ​ Contract Assets and Liabilities ​ Contract assets include unbilled amounts typically resulting from sales under long term contracts when the cost-to-cost method of revenue recognition is used, revenue recognized exceeds the amount billed to the customer and right to payment is conditional or subject to completing a milestone, such as a phase of the project. Contract assets are not considered to have a significant financing component, as they are intended to protect the customer in the event that we do not perform our obligations under the contract. Contract assets are generally classified as current, as it is very unusual for us to have contract assets with a term of greater than one year. ​ Contract liabilities consist of advance payments and billings in excess of revenue recognized. It is very unusual for us to have advanced payments with a term of greater than one year; therefore, our contract liabilities are usually all current. Advanced payments from customers related to work not yet started are classified as “Deferred Revenue.” If we have advanced payments with a term greater than one year, the noncurrent portion of advanced payments would be included in “Other Long-term Liabilities” in our Consolidated Balance Sheets. Contract liabilities are not considered to have a significant financing component, as they are used to meet working capital requirements that are generally higher in the early stages of a contract and are intended to protect us from the other party failing to meet its obligations under the contract. Our contract assets and liabilities are reported in a net position on a contract-by-contract basis at the end of each reporting period. ​ Contract assets and liabilities in the Consolidated Balance Sheet consisted of the following amounts as of March 31, 2023 and December 31, 2022 (in thousands): ​ ​ ​ ​ ​ ​ ​ March 31, 2023 ​ December 31, 2022 Contract assets: ​ ​ ​ ​ ​ Costs and estimated earnings in excess of billings, less allowance for credit losses $ 26,820 ​ $ 27,211 Contract liabilities: ​ ​ ​ ​ ​ Billings in excess of costs and estimated earnings and deferred revenue $ 717,294 ​ $ 548,293 ​ In the first three months of 2023 and 2022, we recognized revenue of $341.9 million and $220.6 million related to our contract liabilities at January 1, 2023 and January 1, 2022, respectively. ​ We did not have any impairment losses recognized on our receivables or contract assets in the first three months of 2023 and 2022. ​ Remaining Performance Obligations ​ Remaining construction performance obligations represent the remaining transaction price of firm orders for which work has not been performed and exclude unexercised contract options. As of March 31, 2023, the aggregate amount of the transaction price allocated to remaining performance obligations was , with the remaining recognized thereafter. Our service maintenance agreements are generally renewable agreements. We have adopted the practical expedient that allows us to not include service maintenance contracts with a total term of year or less; therefore, we do not report unfulfilled performance obligations for service maintenance agreements.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2023
Fair Value Measurements
Fair Value Measurements	4. Fair Value Measurements ​ Interest Rate Risk Management and Derivative Instruments In April 2020, we entered into interest rate swap agreements to reduce our exposure to variable interest rates on our revolving credit facility. The interest rate swap agreements terminated on September 30, 2022. ​ At times, we use derivative instruments to manage exposure to market risk, including interest rate risk. Unsettled amounts under our interest rate swaps, if any, are recorded in the Consolidated Balance Sheet at fair value in “Other Receivables” or “Other Current Liabilities.” Gains and losses on our interest rate swaps are recorded in the Consolidated Income Statement in “Interest Expense.” For the three months ended March 31, 2022, we recognized a net loss of $0.1 million related to our interest rate swaps. We currently do not have any derivatives that are accounted for as hedges under ASC 815. ​ Fair Value Measurement ​ We classify and disclose assets and liabilities carried at fair value in one of the following three categories: ​ ● Level 1—quoted prices in active markets for identical assets and liabilities; ● Level 2—observable market-based inputs or unobservable inputs that are corroborated by market data; and ● Level 3—significant unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions. ​ The following table summarizes the fair values, and levels within the fair value hierarchy in which the fair value measurements are included, for assets and liabilities measured on a recurring basis as of March 31, 2023 and December 31, 2022 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements at March 31, 2023 ​ Level 1 Level 2 Level 3 Total Cash and cash equivalents ​ $ 48,560 ​ $ — ​ $ — ​ $ 48,560 Life insurance—cash surrender value ​ $ — ​ $ 7,136 ​ $ — ​ $ 7,136 Contingent earn-out obligations ​ $ — ​ $ — ​ $ 38,148 ​ $ 38,148 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements at December 31, 2022 ​ Level 1 Level 2 Level 3 Total Cash and cash equivalents ​ $ 57,214 ​ $ — ​ $ — ​ $ 57,214 Life insurance—cash surrender value ​ $ — ​ $ 9,315 ​ $ — ​ $ 9,315 Contingent earn-out obligations ​ $ — ​ $ — ​ $ 32,317 ​ $ 32,317 ​ 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. We believe the carrying value of our debt associated with our revolving credit facility approximates its fair value due to the variable rate on such debt. We believe the carrying values of our notes to former owners approximate their fair values due to the relatively short remaining terms on these notes. We have life insurance policies covering 119 employees with a combined face value of $81.5 million. The policies are invested in several investment vehicles, and the fair value measurement of the cash surrender balance associated with these policies is determined using Level 2 inputs within the fair value hierarchy and will vary with investment performance. The cash surrender value of these policies is 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 and operating income, probabilities of achieving such future cash flows and operating income and a weighted average cost of capital. Significant changes in any of these assumptions could result in a significantly higher or lower potential liability. The contingent earn-out obligations are measured at fair value each reporting period, and changes in estimates of fair value are recognized in earnings. As of March 31, 2023, cash flows were discounted using a weighted average cost of capital ranging from 11.0% - 17.0%. ​ The table below presents a reconciliation of the fair value of our contingent earn-out obligations that use significant unobservable inputs (Level 3) (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Year Ended ​ ​ March 31, 2023 ​ December 31, 2022 ​ Balance at beginning of period $ 32,317 $ 34,114 Issuances ​ 3,449 ​ — ​ ​ Settlements ​ ​ — ​ ​ (6,616) ​ ​ Adjustments to fair value ​ 2,382 ​ 4,819 ​ ​ Balance at end of period ​ $ 38,148 ​ $ 32,317 ​ ​ ​

Acquisitions

Acquisitions	3 Months Ended
	Mar. 31, 2023
Acquisitions
Acquisitions	5. Acquisitions ​ On February 1, 2023, we acquired all of the issued and outstanding shares of capital stock of Eldeco, Inc. (“Eldeco”), headquartered in South Carolina, for a total preliminary purchase price of $73.9 million, which included $60.8 million of cash paid on the closing date, $8.0 million in notes payable to the former owners, an earn-out that will be paid if certain financial targets are met after the acquisition date and a working capital adjustment. Eldeco performs electrical design and construction services in the Southeastern region of the United States. As a result of the acquisition, Eldeco is a wholly owned subsidiary of the Company reported in our electrical services segment. ​ On April 1, 2022, we acquired Atlantic Electric, LLC and its related subsidiary (“Atlantic”), headquartered in Charleston, South Carolina, and with operations in South Carolina and Western North Carolina, for a total purchase price of $48.1 million, which included $34.1 million of cash paid on the closing date, $5.3 million in notes payable to former owners and a working capital adjustment. Atlantic performs electrical contracting for customers in various South Carolina markets, as well as installation of airport runway lighting in the Southeast. As a result of the acquisition, Atlantic is a wholly owned subsidiary of the Company reported in our electrical services segment. ​ The results of operations of acquisitions are included in our consolidated financial statements from their respective acquisition dates. Our Consolidated Balance Sheet includes preliminary allocations of the purchase price to the assets acquired and liabilities assumed for the applicable acquisitions pending the completion of the final valuation of intangible assets and accrued liabilities. The acquisitions completed in the current and prior year were not material, individually or in the aggregate. Additional contingent purchase price (“earn-out”) has been or will be paid if certain acquisitions achieve predetermined profitability targets. Such earn-outs, when they are not subject to the continued employment of the sellers, are estimated as of the purchase date and included as part of the consideration paid for the acquisition. If we have an earn-out under which continued employment is a condition to receipt of payment, then the earn-out is recorded as compensation expense over the period earned.

Goodwill and Identifiable Intan

Goodwill and Identifiable Intangible Assets, Net	3 Months Ended
	Mar. 31, 2023
Goodwill and Identifiable Intangible Assets, Net
Goodwill and Identifiable Intangible Assets, Net	6. Goodwill and Identifiable Intangible Assets, Net ​ Goodwill ​ The changes in the carrying amount of goodwill are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mechanical Services ​ Electrical Services ​ ​ ​ ​ Segment Segment ​ Total Balance at December 31, 2021 ​ $ 361,320 ​ $ 230,794 ​ $ 592,114 ​ Acquisitions and purchase price adjustments (See Note 5) ​ 2,609 ​ ​ 17,066 ​ ​ 19,675 ​ Balance at December 31, 2022 ​ ​ 363,929 ​ ​ 247,860 ​ ​ 611,789 ​ Acquisitions and purchase price adjustments (See Note 5) ​ ​ — ​ ​ 25,645 ​ ​ 25,645 ​ Balance at March 31, 2023 ​ $ 363,929 ​ $ 273,505 ​ $ 637,434 ​ ​ Identifiable Intangible Assets, Net ​ At March 31, 2023, future amortization expense of identifiable intangible assets is as follows (in thousands): ​ ​ ​ ​ ​ ​ Year ending December 31— ​ ​ 2023 (remainder of the year) ​ $ 32,256 ​ 2024 ​ 37,006 ​ 2025 ​ 34,525 ​ 2026 ​ 33,681 ​ 2027 ​ ​ 31,699 ​ Thereafter ​ 126,903 ​ Total ​ $ 296,070 ​ ​

Debt Obligations

Debt Obligations	3 Months Ended
	Mar. 31, 2023
Debt Obligations
Debt Obligations	7. Debt Obligations ​ Debt obligations consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, ​ December 31, ​ ​ 2023 2022 Revolving credit facility ​ $ 160,000 ​ $ 215,000 ​ Notes to former owners ​ ​ 49,040 ​ 41,040 ​ Other debt ​ ​ 189 ​ ​ 205 ​ Total debt ​ ​ 209,229 ​ ​ 256,245 ​ Less—current portion ​ ​ (11,468) ​ (9,000) ​ Total long-term portion of debt ​ $ 197,761 ​ $ 247,245 ​ ​ Revolving Credit Facility ​ On May 25, 2022, we amended our senior credit facility (as amended, the “Facility”) arranged by Wells Fargo Bank, National Association, as administrative agent, and provided by a syndicate of banks, increasing our borrowing capacity to $850 million. As amended, the Facility is composed of a revolving credit line guaranteed by certain of our subsidiaries, in the amount of $850.0 million, and the previous term loan has been eliminated. The amended Facility also provides for an accordion or increase option not to exceed the greater of (a) $250 million and (b) 1.0x Credit Facility Adjusted EBITDA (as defined below), as well as a sublimit of up to $175.0 million issuable in the form of letters of credit. The Facility expires in July 2027 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 the equity of, and assets held by, certain unrestricted subsidiaries and our wholly owned captive insurance company, and a second lien on our assets related to projects subject to surety bonds. In 2022, we incurred approximately $2.3 million in financing and professional costs in connection with the amendment to the Facility, which, combined with previously unamortized costs of $1.2 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 March 31, 2023, we had $160.0 million of outstanding borrowings on the revolving credit facility, $51.9 million in letters of credit outstanding and $638.1 million of credit available. ​ There are two interest rate options for borrowings under the Facility, the Base Rate Loan (as defined in the Facility) option and the Secured Overnight Financing Rate (“SOFR”) 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: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net Leverage Ratio ​ ​ Less than 1.00 1.00 to less than 1.75 1.75 to less than 2.50 2.50 to less than 3.00 3.00 or greater ​ Additional Per Annum Interest Margin Added Under: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Base Rate Loan Option ​ 0.00 % 0.25 % 0.50 % 0.75 % 1.00 % SOFR Loan Option ​ 1.00 % 1.25 % 1.50 % 1.75 % 2.00 % ​ The weighted average interest rate applicable to the borrowings under the revolving credit facility was approximately 6.2% as of March 31, 2023 and 5.7% as of December 31, 2022. ​ 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. The letter of credit fees range from 1.00% to 2.00% per annum, based on the Net Leverage Ratio. ​ 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 0.15% to 0.25% per annum, based on the Net Leverage Ratio. ​ 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. We were in compliance with all of our financial covenants as of March 31, 2023. ​ Notes to Former Owners ​ As part of the consideration used to acquire eleven companies, we have outstanding notes to the former owners. Together, these notes had an outstanding balance of $49.0 million as of March 31, 2023. At March 31, 2023, future principal payments of notes to former owners by maturity year are as follows (dollars in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at ​ Range of Stated ​ March 31, 2023 ​ Interest Rates 2023 ​ $ 11,400 ​ 2.5 - 3.0 % 2024 ​ 4,800 ​ 2.5 % 2025 ​ 22,215 ​ 2.25 - 3.0 % 2026 ​ 10,625 ​ 2.5 - 3.75 % Total ​ $ 49,040 ​ ​ ​ ​ ​ F

Leases

Leases	3 Months Ended
	Mar. 31, 2023
Leases
Leases	8. Leases ​ We lease certain facilities, vehicles and equipment primarily under noncancelable operating leases. The most significant portion of these noncancelable operating leases is for the facilities occupied by our corporate office and our operating locations. Leases with an initial term of 12 months or less are not recorded in the Consolidated Balance Sheet. We do not separate lease components from their associated non-lease components pursuant to lease accounting guidance. We have certain leases with variable payments based on an index as well as some short-term leases on equipment and facilities. Variable lease expense and short-term lease expense were not material to our financial statements and aggregated to $10.2 million and $4.1 million in the first three months of 2023 and 2022, respectively. Lease right-of-use assets and liabilities are recognized at commencement date based on the present value of lease payments over the lease term. As most of our leases do not provide an implicit rate, we generally use our incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. The weighted average discount rate for our operating leases as of March 31, 2023 and December 31, 2022 was 4.5% and 4.3%, respectively. We recognize operating lease expense, including escalating lease payments and lease incentives, on a straight-line basis over the lease term. Operating lease expense for the three months ended March 31, 2023 and 2022 was $17.3 million and $10.4 million, respectively. ​ The lease terms generally range from three ​ A majority of the Company’s real property leases are with individuals or entities with whom we have no other business relationship. However, in certain instances the Company enters into real property leases with current or former employees. Rent paid to related parties for the three months ended March 31, 2023 and 2022 was approximately $2.0 million and $1.7 million, respectively. ​ If we decide to cancel or terminate a lease before the end of its term, we would typically owe the lessor the remaining lease payments under the term of the lease. Our lease agreements do not contain any material residual value guarantees or material restrictive covenants. On rare occasions, we rent or sublease certain real estate assets that we no longer use to third parties. ​ The following table summarizes the operating lease assets and liabilities included in the Consolidated Balance Sheet as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2023 ​ December 31, 2022 ​ Operating lease right-of-use assets $ 134,755 ​ $ 130,666 ​ Operating lease liabilities: ​ ​ ​ ​ ​ ​ Other current liabilities $ 21,487 ​ $ 21,151 ​ Long-term operating lease liabilities ​ 115,018 ​ ​ 111,744 ​ Total operating lease liabilities $ 136,505 ​ $ 132,895 ​ ​ The maturities of operating lease liabilities are as follows (in thousands): ​ ​ ​ ​ ​ Year ending December 31— ​ ​ ​ 2023 (excluding the three months ended March 31, 2023) ​ $ 20,511 2024 ​ ​ 25,536 2025 ​ ​ 24,269 2026 ​ ​ 20,734 2027 ​ ​ 16,543 Thereafter ​ ​ 55,679 Total Lease Payments ​ ​ 163,272 Less—Present Value Discount ​ ​ (26,767) Present Value of Operating Lease Liabilities ​ $ 136,505 ​ Supplemental information related to operating leases was as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ 2023 ​ 2022 Cash paid for amounts included in the measurement of operating lease liabilities $ 7,024 ​ $ 6,314 Operating lease right-of-use assets obtained in exchange for lease liabilities $ 9,446 ​ $ 4,914 ​

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2023
Commitments and Contingencies
Commitments and Contingencies	9. 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. ​ During the first quarter of 2023, we recorded a pre-tax gain of $6.8 million from legal developments and settlements that primarily relate to disputes with customers regarding the outcome of completed projects as well as an obligation to perform subcontract work under two executed letters of intent for subsequent projects that we believed were not enforceable. The pre-tax gain of $6.8 million has been recorded as an increase in gross profit of $6.6 million, a reduction in SG&A of $0.7 million, an increase in interest income of $1.3 million and an increase in the change in fair value of contingent earn-out obligations expense of $1.8 million in our Consolidated Statements of Operations. ​ As of March 31, 2023, we recorded an accrual for unresolved matters, which is not material to our financial statements, based on our analysis of likely outcomes related to the respective matters; however, it is possible that the ultimate outcome and associated costs will deviate from our estimates and that, in the event of an unexpectedly adverse outcome, we may experience additional costs and expenses in future periods. ​ Surety ​ Many customers, particularly in connection with new construction, require us to post performance and payment bonds issued by a financial institution known as a surety. If we fail to perform under the terms of a contract or to pay subcontractors and vendors who provided goods or services under a contract, the customer may demand that the surety make payments or provide services under the bond. We must reimburse the surety for any expenses or outlays it incurs. ​ Current market conditions for surety markets and bonding capacity are adequate, with acceptable terms and conditions. Historically, approximately 10% to 20% 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. ​

Stockholders' Equity

Stockholders' Equity	3 Months Ended
	Mar. 31, 2023
Stockholders' Equity
Stockholders' Equity	10. 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, 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 zero anti-dilutive stock options excluded from the calculation of diluted EPS for the three months ended March 31, 2023 and 2022, respectively. ​ The following table reconciles the number of shares outstanding with the number of shares used in computing basic and diluted earnings per share for each of the periods presented (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ March 31, ​ ​ 2023 2022 Common shares outstanding, end of period ​ 35,752 35,953 ​ Effect of using weighted average common shares outstanding ​ 60 123 ​ Shares used in computing earnings per share—basic ​ 35,812 36,076 ​ Effect of shares issuable under stock option plans based on the treasury stock method ​ 26 43 ​ Effect of restricted and contingently issuable shares ​ 69 69 ​ Shares used in computing earnings per share—diluted ​ 35,907 36,188 ​ ​ 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 increased the number of shares that may be acquired under the program and approved extensions of the program. On May 17, 2022, the Board approved an extension to the program by increasing the shares authorized for repurchase by 0.7 million shares. Since the inception of the repurchase program, the Board has approved 10.9 million shares to be repurchased. As of March 31, 2023, we have repurchased a cumulative total of 10.1 million shares at an average price of $24.80 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 three months ended March 31, 2023, we repurchased less than 0.1 million shares for approximately $3.6 million at an average price of $121.36 per share.

Segment Information

Segment Information	3 Months Ended
	Mar. 31, 2023
Segment Information
Segment Information	11. Segment Information Our activities are within the mechanical services industry and the electrical services industry, which represent our two reportable segments. We aggregate our operating segments into two reportable segments, as the operating segments meet all of the aggregation criteria. The following tables present information about our reportable segments (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, 2023 ​ Mechanical Services Electrical Services Corporate Consolidated Revenue ​ $ 918,615 ​ $ 256,025 ​ $ — ​ $ 1,174,640 Gross Profit ​ $ 164,067 ​ $ 41,338 ​ $ — ​ $ 205,405 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, 2022 ​ Mechanical Services Electrical Services Corporate Consolidated Revenue ​ $ 682,511 ​ $ 202,705 ​ $ — ​ $ 885,216 Gross Profit ​ $ 126,728 ​ $ 26,416 ​ $ — ​ $ 153,144 ​ ​

Summary of Significant Accoun_2

Summary of Significant Accounting Policies and Estimates (Policies)	3 Months Ended
	Mar. 31, 2023
Summary of Significant Accounting Policies and Estimates
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, 2022 (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. The results of operations for interim periods are not necessarily indicative of the results for the full fiscal year. Certain amounts in prior periods 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	Use of Estimates ​ The preparation of financial statements in conformity with generally accepted accounting principles requires the use of estimates and assumptions by management in determining the reported amounts of assets and liabilities, revenue and expenses and disclosures regarding contingent assets and liabilities. Actual results could differ from those estimates. The most significant estimates used in our financial statements affect revenue and cost recognition for construction contracts, self-insurance accruals, accounting for income taxes, 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 ​ Recently Adopted Accounting Pronouncements ​ In October 2021, the FASB issued ASU 2021-08, “Business Combinations (Topic 805): Accounting for Contract Assets and Contract Liabilities from Contracts with Customers.” This standard requires an acquirer to apply Accounting Standards Codification Topic 606 to recognize and measure contract assets and contract liabilities in a business combination. ASU 2021-08 is effective for fiscal years beginning after December 15, 2022 and interim periods within that year. We adopted this standard on January 1, 2023, and the impact was not material on our consolidated financial statements. ​
Revenue Recognition	Revenue Recognition ​ We recognize revenue over time for all of our services as we perform them because (i) control continuously transfers to that customer as work progresses, and (ii) we have the right to bill the customer as costs are incurred. The customer typically controls the work in process, as evidenced either by contractual termination clauses or by our rights to payment for work performed to date, plus a reasonable profit, for delivery of products or services that do not have an alternative use to the Company. ​ For the reasons listed above, revenue is recognized based on the extent of progress towards completion of the performance obligation. The selection of the method to measure progress towards completion requires judgment and is based on the nature of the products or services to be provided. We generally use a cost-to-cost input method to measure our progress towards satisfaction of the performance obligation for our contracts, as it best depicts the transfer of assets to the customer that occurs as we incur costs on our contracts. Under the cost-to-cost input method, the extent of progress towards completion is measured based on the ratio of costs incurred to date to the total estimated costs at completion of the performance obligation. Revenue, including estimated fees or profits, is recorded proportionally as costs are incurred. Costs to fulfill include labor, materials, subcontractors’ costs, other direct costs and an allocation of indirect costs. ​ For a small portion of our business in which our services are delivered in the form of service maintenance agreements for existing systems to be repaired and maintained, as opposed to constructed, our performance obligation is to maintain the customer’s mechanical system for a specific period of time. Similar to construction jobs, we recognize revenue over time; however, for service maintenance agreements in which the full cost to provide services may not be known, we generally use an input method to recognize revenue, which is based on the amount of time we have provided our services out of the total time we have been contracted to perform those services. Our revenue recognition policy is further discussed in Note 3 “Revenue from Contracts with Customers.” ​
Accounts Receivable and Allowance for Credit Losses	Accounts Receivable and Allowance for Credit Losses ​ We are required to estimate and record the expected credit losses over the contractual life of our financial assets measured at amortized cost, including billed and unbilled accounts receivable, other receivables and contract assets. Accounts receivable include amounts from work completed in which we have billed or have an unconditional right to bill our customers. Our trade receivables are contractually due in less than a year. ​ We estimate our credit losses using a loss-rate method for each of our identified portfolio segments. Our portfolio segments are construction, service and other. While our construction and service financial assets are often with the same subset of customers and industries, our construction financial assets will generally have a lower loss-rate than service financial assets due to lien rights, which we are more likely to have on construction jobs. These lien rights result in lower credit loss expenses on average compared to receivables that do not have lien rights. Financial assets classified as Other include receivables that are not related to our core revenue producing activities, such as receivables related to our acquisition activity from former owners, our vendor rebate program or receivables for estimated losses in excess of our insurance deductible, which are accrued with a corresponding accrued insurance liability. ​ Loss rates for our portfolios are based on numerous factors, including our history of credit loss expense by portfolio, the financial strength of our customers and counterparties in each portfolio, the aging of our receivables, our expectation of likelihood of payment, macroeconomic trends in the U.S. and the current and forecasted nonresidential construction market trends in the U.S. ​ In addition to the loss-rate calculations discussed above, we also record allowance for credit losses for specific receivables that are deemed to have a higher risk profile than the rest of the respective pool of receivables (e.g., when we hold concerns about a specific customer going bankrupt and no longer being able to pay the receivables due to us). ​
Income Taxes	Income Taxes ​ We conduct business throughout the United States in virtually all fifty states. Our effective tax rate changes based upon our relative profitability, or lack thereof, in the federal and various state jurisdictions with differing tax rates and rules. In addition, discrete items such as tax law changes, judgments and legal structures, can impact our effective tax rate. These items can also include the tax treatment for impairment of goodwill and other intangible assets, changes in fair value of acquisition-related assets and liabilities, uncertain tax positions, and accounting for losses associated with underperforming operations. ​ Following an Internal Revenue Service survey of previously filed refund claims for the 2016, 2017 and 2018 tax years, the Joint Committee on Taxation approved such refunds in late January 2022. As a result, our benefit for income taxes in the first quarter of 2022 included a $28.8 million reduction in unrecognized tax benefits plus approximately $1.6 million of net interest income on the refunds. ​ Our benefit for income taxes in the first quarter of 2022 was further increased by $26.8 million for the expected refunds due to our intention to claim the R&D tax credit for the 2019, 2020 and 2021 tax years. In the third quarter of 2022, we claimed the R&D tax credit on our originally filed 2021 federal return and recognized an additional $1.7 million benefit for the 2019, 2020 and 2021 tax years. Additionally, in February 2023, we filed amended federal returns for 2019 and 2020 requesting refunds primarily from claiming the R&D tax credit. ​ The Inflation Reduction Act was enacted on August 16, 2022. This law, among other provisions, provides a corporate alternative minimum tax on adjusted financial statement income over $1 billion, which is effective for tax years beginning after December 31, 2022, and a 1% excise tax on net corporate stock repurchases after December 31, 2022. The impact of the excise tax is recorded in “Treasury Stock” within our Consolidated Balance Sheet. We currently believe these provisions will be immaterial to our overall financial results, financial position and cash flows.
Financial Instruments	Financial Instruments ​ Our financial instruments consist of cash and cash equivalents, accounts receivable, other receivables, accounts payable and life insurance policies, for which we deem the carrying values approximate their fair value due to the short-term nature of these instruments, as well as notes to former owners and a revolving credit facility.
Unbilled Accounts Receivable	Unbilled Accounts Receivable ​ Unbilled Accounts Receivable are amounts due to us that we have earned under a contract where our right to payment is unconditional. A right to consideration is unconditional if only the passage of time is required before payment of the consideration is due.
Investments	Investments ​ We have a $2.5 million investment with a fair value that is not readily determinable and is recorded at cost. This investment is included in “Other Noncurrent Assets” in our Consolidated Balance Sheet and is reviewed quarterly for impairment. We did not recognize any impairments in the current year related to this investment.
Leases	We lease certain facilities, vehicles and equipment primarily under noncancelable operating leases. The most significant portion of these noncancelable operating leases is for the facilities occupied by our corporate office and our operating locations. Leases with an initial term of 12 months or less are not recorded in the Consolidated Balance Sheet. We do not separate lease components from their associated non-lease components pursuant to lease accounting guidance. We have certain leases with variable payments based on an index as well as some short-term leases on equipment and facilities. Variable lease expense and short-term lease expense were not material to our financial statements and aggregated to $10.2 million and $4.1 million in the first three months of 2023 and 2022, respectively. Lease right-of-use assets and liabilities are recognized at commencement date based on the present value of lease payments over the lease term. As most of our leases do not provide an implicit rate, we generally use our incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. The weighted average discount rate for our operating leases as of March 31, 2023 and December 31, 2022 was 4.5% and 4.3%, respectively. We recognize operating lease expense, including escalating lease payments and lease incentives, on a straight-line basis over the lease term. Operating lease expense for the three months ended March 31, 2023 and 2022 was $17.3 million and $10.4 million, respectively. ​ The lease terms generally range from three ​ A majority of the Company’s real property leases are with individuals or entities with whom we have no other business relationship. However, in certain instances the Company enters into real property leases with current or former employees. Rent paid to related parties for the three months ended March 31, 2023 and 2022 was approximately $2.0 million and $1.7 million, respectively. ​ If we decide to cancel or terminate a lease before the end of its term, we would typically owe the lessor the remaining lease payments under the term of the lease. Our lease agreements do not contain any material residual value guarantees or material restrictive covenants. On rare occasions, we rent or sublease certain real estate assets that we no longer use to third parties.

Revenue from Contracts with C_2

Revenue from Contracts with Customers (Tables)	3 Months Ended
	Mar. 31, 2023
Revenue from Contracts with Customers
Schedule of disaggregation of revenue	See details in the following tables (dollars in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ ​ Revenue by Service Provided 2023 ​ 2022 ​ Mechanical Services ​ $ 918,615 78.2 % ​ $ 682,511 77.1 % ​ Electrical Services ​ ​ 256,025 ​ 21.8 % ​ ​ 202,705 ​ 22.9 % ​ Total ​ $ 1,174,640 ​ 100.0 % ​ $ 885,216 ​ 100.0 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ ​ Revenue by Type of Customer ​ 2023 ​ ​ 2022 ​ Manufacturing ​ $ 366,356 ​ 31.2 % ​ $ 314,729 ​ 35.5 % ​ Technology ​ ​ 226,249 ​ 19.3 % ​ ​ 95,455 ​ 10.8 % ​ Healthcare ​ ​ 159,815 ​ 13.5 % ​ ​ 134,795 ​ 15.2 % ​ Education ​ ​ 110,253 ​ 9.4 % ​ ​ 89,446 ​ 10.1 % ​ Office Buildings ​ ​ 98,195 ​ 8.4 % ​ ​ 75,115 ​ 8.5 % ​ Retail, Restaurants and Entertainment ​ ​ 76,194 ​ 6.5 % ​ ​ 65,582 ​ 7.4 % ​ Government ​ ​ 64,415 ​ 5.5 % ​ ​ 57,465 ​ 6.5 % ​ Multi-Family and Residential ​ ​ 45,007 ​ 3.8 % ​ ​ 24,442 ​ 2.8 % ​ Other ​ ​ 28,156 ​ 2.4 % ​ ​ 28,187 ​ 3.2 % ​ Total ​ $ 1,174,640 ​ 100.0 % ​ $ 885,216 ​ 100.0 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ ​ Revenue by Activity Type ​ 2023 ​ ​ 2022 ​ New Construction ​ $ 627,952 ​ 53.5 % ​ $ 429,418 ​ 48.5 % ​ Existing Building Construction ​ ​ 309,483 ​ 26.3 % ​ ​ 259,285 ​ 29.3 % ​ Service Projects ​ ​ 103,105 ​ 8.8 % ​ ​ 76,252 ​ 8.6 % ​ Service Calls, Maintenance and Monitoring ​ ​ 134,100 ​ 11.4 % ​ ​ 120,261 ​ 13.6 % ​ Total ​ $ 1,174,640 ​ 100.0 % ​ $ 885,216 ​ 100.0 % ​ ​
Schedule of contract assets and liabilities	Contract assets and liabilities in the Consolidated Balance Sheet consisted of the following amounts as of March 31, 2023 and December 31, 2022 (in thousands): ​ ​ ​ ​ ​ ​ ​ March 31, 2023 ​ December 31, 2022 Contract assets: ​ ​ ​ ​ ​ Costs and estimated earnings in excess of billings, less allowance for credit losses $ 26,820 ​ $ 27,211 Contract liabilities: ​ ​ ​ ​ ​ Billings in excess of costs and estimated earnings and deferred revenue $ 717,294 ​ $ 548,293 ​

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2023
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	The following table summarizes the fair values, and levels within the fair value hierarchy in which the fair value measurements are included, for assets and liabilities measured on a recurring basis as of March 31, 2023 and December 31, 2022 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements at March 31, 2023 ​ Level 1 Level 2 Level 3 Total Cash and cash equivalents ​ $ 48,560 ​ $ — ​ $ — ​ $ 48,560 Life insurance—cash surrender value ​ $ — ​ $ 7,136 ​ $ — ​ $ 7,136 Contingent earn-out obligations ​ $ — ​ $ — ​ $ 38,148 ​ $ 38,148 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements at December 31, 2022 ​ Level 1 Level 2 Level 3 Total Cash and cash equivalents ​ $ 57,214 ​ $ — ​ $ — ​ $ 57,214 Life insurance—cash surrender value ​ $ — ​ $ 9,315 ​ $ — ​ $ 9,315 Contingent earn-out obligations ​ $ — ​ $ — ​ $ 32,317 ​ $ 32,317 ​
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): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Year Ended ​ ​ March 31, 2023 ​ December 31, 2022 ​ Balance at beginning of period $ 32,317 $ 34,114 Issuances ​ 3,449 ​ — ​ ​ Settlements ​ ​ — ​ ​ (6,616) ​ ​ Adjustments to fair value ​ 2,382 ​ 4,819 ​ ​ Balance at end of period ​ $ 38,148 ​ $ 32,317 ​ ​

Goodwill and Identifiable Int_2

Goodwill and Identifiable Intangible Assets, Net (Tables)	3 Months Ended
	Mar. 31, 2023
Goodwill and Identifiable Intangible Assets, Net
Schedule of changes in the carrying amount of goodwill	The changes in the carrying amount of goodwill are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mechanical Services ​ Electrical Services ​ ​ ​ ​ Segment Segment ​ Total Balance at December 31, 2021 ​ $ 361,320 ​ $ 230,794 ​ $ 592,114 ​ Acquisitions and purchase price adjustments (See Note 5) ​ 2,609 ​ ​ 17,066 ​ ​ 19,675 ​ Balance at December 31, 2022 ​ ​ 363,929 ​ ​ 247,860 ​ ​ 611,789 ​ Acquisitions and purchase price adjustments (See Note 5) ​ ​ — ​ ​ 25,645 ​ ​ 25,645 ​ Balance at March 31, 2023 ​ $ 363,929 ​ $ 273,505 ​ $ 637,434 ​ ​
Schedule of future amortization expense of identifiable intangible assets	At March 31, 2023, future amortization expense of identifiable intangible assets is as follows (in thousands): ​ ​ ​ ​ ​ ​ Year ending December 31— ​ ​ 2023 (remainder of the year) ​ $ 32,256 ​ 2024 ​ 37,006 ​ 2025 ​ 34,525 ​ 2026 ​ 33,681 ​ 2027 ​ ​ 31,699 ​ Thereafter ​ 126,903 ​ Total ​ $ 296,070 ​

Debt Obligations (Tables)

Debt Obligations (Tables)	3 Months Ended
	Mar. 31, 2023
Schedule of components of debt obligations	Debt obligations consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, ​ December 31, ​ ​ 2023 2022 Revolving credit facility ​ $ 160,000 ​ $ 215,000 ​ Notes to former owners ​ ​ 49,040 ​ 41,040 ​ Other debt ​ ​ 189 ​ ​ 205 ​ Total debt ​ ​ 209,229 ​ ​ 256,245 ​ Less—current portion ​ ​ (11,468) ​ (9,000) ​ Total long-term portion of debt ​ $ 197,761 ​ $ 247,245 ​ ​
Summary of additional margins	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net Leverage Ratio ​ ​ Less than 1.00 1.00 to less than 1.75 1.75 to less than 2.50 2.50 to less than 3.00 3.00 or greater ​ Additional Per Annum Interest Margin Added Under: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Base Rate Loan Option ​ 0.00 % 0.25 % 0.50 % 0.75 % 1.00 % SOFR Loan Option ​ 1.00 % 1.25 % 1.50 % 1.75 % 2.00 % ​
Notes to Former Owners
Schedule of future principal payments of notes to former owners	At March 31, 2023, future principal payments of notes to former owners by maturity year are as follows (dollars in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at ​ Range of Stated ​ March 31, 2023 ​ Interest Rates 2023 ​ $ 11,400 ​ 2.5 - 3.0 % 2024 ​ 4,800 ​ 2.5 % 2025 ​ 22,215 ​ 2.25 - 3.0 % 2026 ​ 10,625 ​ 2.5 - 3.75 % Total ​ $ 49,040 ​ ​ ​ ​

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2023
Leases
Schedule of operating lease assets and liabilities	The following table summarizes the operating lease assets and liabilities included in the Consolidated Balance Sheet as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2023 ​ December 31, 2022 ​ Operating lease right-of-use assets $ 134,755 ​ $ 130,666 ​ Operating lease liabilities: ​ ​ ​ ​ ​ ​ Other current liabilities $ 21,487 ​ $ 21,151 ​ Long-term operating lease liabilities ​ 115,018 ​ ​ 111,744 ​ Total operating lease liabilities $ 136,505 ​ $ 132,895 ​ ​
Schedule of maturities of lease liabilities	The maturities of operating lease liabilities are as follows (in thousands): ​ ​ ​ ​ ​ Year ending December 31— ​ ​ ​ 2023 (excluding the three months ended March 31, 2023) ​ $ 20,511 2024 ​ ​ 25,536 2025 ​ ​ 24,269 2026 ​ ​ 20,734 2027 ​ ​ 16,543 Thereafter ​ ​ 55,679 Total Lease Payments ​ ​ 163,272 Less—Present Value Discount ​ ​ (26,767) Present Value of Operating Lease Liabilities ​ $ 136,505 ​
Schedule of supplemental information related to leases	Supplemental information related to operating leases was as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ 2023 ​ 2022 Cash paid for amounts included in the measurement of operating lease liabilities $ 7,024 ​ $ 6,314 Operating lease right-of-use assets obtained in exchange for lease liabilities $ 9,446 ​ $ 4,914

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	3 Months Ended
	Mar. 31, 2023
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, ​ ​ 2023 2022 Common shares outstanding, end of period ​ 35,752 35,953 ​ Effect of using weighted average common shares outstanding ​ 60 123 ​ Shares used in computing earnings per share—basic ​ 35,812 36,076 ​ Effect of shares issuable under stock option plans based on the treasury stock method ​ 26 43 ​ Effect of restricted and contingently issuable shares ​ 69 69 ​ Shares used in computing earnings per share—diluted ​ 35,907 36,188 ​ ​

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2023
Segment Information
Summary of information about reportable segments	The following tables present information about our reportable segments (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, 2023 ​ Mechanical Services Electrical Services Corporate Consolidated Revenue ​ $ 918,615 ​ $ 256,025 ​ $ — ​ $ 1,174,640 Gross Profit ​ $ 164,067 ​ $ 41,338 ​ $ — ​ $ 205,405 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, 2022 ​ Mechanical Services Electrical Services Corporate Consolidated Revenue ​ $ 682,511 ​ $ 202,705 ​ $ — ​ $ 885,216 Gross Profit ​ $ 126,728 ​ $ 26,416 ​ $ — ​ $ 153,144 ​

Summary of Significant Accoun_3

Summary of Significant Accounting Policies and Estimates - Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2022	Mar. 31, 2022
Summary of Significant Accounting Policies and Estimates
Reduced provision for income taxes		$ 28.8
Net interest income on the tax refunds		1.6
Total Tax Years 2019-2021
Summary of Significant Accounting Policies and Estimates
R&D tax credits	$ 1.7	$ 26.8

Summary of Significant Accoun_4

Summary of Significant Accounting Policies and Estimates - Investments (Details) $ in Millions	Mar. 31, 2023 USD ($)
Summary of Significant Accounting Policies and Estimates
Investment fair value	$ 2.5

Revenue from Contracts with C_3

Revenue from Contracts with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Disaggregation of Revenue
Revenue	$ 1,174,640	$ 885,216
Percentage of revenue from contract with customer (as a percent)	100%	100%
Manufacturing
Disaggregation of Revenue
Revenue	$ 366,356	$ 314,729
Percentage of revenue from contract with customer (as a percent)	31.20%	35.50%
Technology
Disaggregation of Revenue
Revenue	$ 226,249	$ 95,455
Percentage of revenue from contract with customer (as a percent)	19.30%	10.80%
Healthcare
Disaggregation of Revenue
Revenue	$ 159,815	$ 134,795
Percentage of revenue from contract with customer (as a percent)	13.50%	15.20%
Education
Disaggregation of Revenue
Revenue	$ 110,253	$ 89,446
Percentage of revenue from contract with customer (as a percent)	9.40%	10.10%
Office Buildings
Disaggregation of Revenue
Revenue	$ 98,195	$ 75,115
Percentage of revenue from contract with customer (as a percent)	8.40%	8.50%
Retail, Restaurants and Entertainment
Disaggregation of Revenue
Revenue	$ 76,194	$ 65,582
Percentage of revenue from contract with customer (as a percent)	6.50%	7.40%
Government
Disaggregation of Revenue
Revenue	$ 64,415	$ 57,465
Percentage of revenue from contract with customer (as a percent)	5.50%	6.50%
Multi-Family and Residential
Disaggregation of Revenue
Revenue	$ 45,007	$ 24,442
Percentage of revenue from contract with customer (as a percent)	3.80%	2.80%
Other
Disaggregation of Revenue
Revenue	$ 28,156	$ 28,187
Percentage of revenue from contract with customer (as a percent)	2.40%	3.20%
New Construction
Disaggregation of Revenue
Revenue	$ 627,952	$ 429,418
Percentage of revenue from contract with customer (as a percent)	53.50%	48.50%
Existing Building Construction
Disaggregation of Revenue
Revenue	$ 309,483	$ 259,285
Percentage of revenue from contract with customer (as a percent)	26.30%	29.30%
Service Projects
Disaggregation of Revenue
Revenue	$ 103,105	$ 76,252
Percentage of revenue from contract with customer (as a percent)	8.80%	8.60%
Service Calls, Maintenance and Monitoring
Disaggregation of Revenue
Revenue	$ 134,100	$ 120,261
Percentage of revenue from contract with customer (as a percent)	11.40%	13.60%
Mechanical Services
Disaggregation of Revenue
Revenue	$ 918,615	$ 682,511
Percentage of revenue from contract with customer (as a percent)	78.20%	77.10%
Electrical Services
Disaggregation of Revenue
Revenue	$ 256,025	$ 202,705
Percentage of revenue from contract with customer (as a percent)	21.80%	22.90%

Revenue from Contracts with C_4

Revenue from Contracts with Customers - Contract Assets and Liabilities (Details) - USD ($)	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Contract Assets
Costs and estimated earnings in excess of billings, less allowance for credit losses	$ 26,820,000		$ 27,211,000
Contract Liabilities
Billings in excess of costs and estimated earnings and deferred revenue	717,294,000		$ 548,293,000
Revenue related to our contract liabilities	341,900,000	$ 220,600,000
Impairment losses	$ 0	$ 0

Revenue from Contracts with C_5

Revenue from Contracts with Customers - Remaining Performance Obligations (Details) $ in Millions	3 Months Ended
	Mar. 31, 2023 USD ($)
Remaining Performance Obligations
The term of the renewable service maintenance agreements (in years)	1 year
Practical Expedient	true
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-04-01
Remaining Performance Obligations
Remaining performance obligations	$ 4,440
Expected timing of performance obligations	12 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-04-01 | Minimum
Remaining Performance Obligations
Expected percentage of remaining performance obligations	65%
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-04-01 | Maximum
Remaining Performance Obligations
Expected percentage of remaining performance obligations	75%

Fair Value Measurements (Detail

Fair Value Measurements (Details) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2023 USD ($) employee	Mar. 31, 2022 USD ($)	Dec. 31, 2022 USD ($)
Fair Value Measurements
Number of employees covered under life insurance policies | employee	119
Combined face value of life insurance policies	$ 81,500
Minimum
Fair Value Measurements
Weighted average cost of capital	11%
Maximum
Fair Value Measurements
Weighted average cost of capital	17%
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 period	$ 32,317	$ 34,114	$ 34,114
Issuances	3,449
Settlements			(6,616)
Adjustments to fair value	2,382		4,819
Balance at end of period	38,148		32,317
Recurring basis | Total
Fair Value Measurements
Cash and cash equivalents	48,560		57,214
Life insurance-cash surrender value	7,136		9,315
Contingent earn-out obligations	38,148		32,317
Recurring basis | Quoted Market Prices In Active Markets for Identical Assets (Level 1)
Fair Value Measurements
Cash and cash equivalents	48,560		57,214
Recurring basis | Significant Other Observable Inputs (Level 2)
Fair Value Measurements
Life insurance-cash surrender value	7,136		9,315
Recurring basis | Significant Unobservable Inputs (Level 3)
Fair Value Measurements
Contingent earn-out obligations	$ 38,148		$ 32,317
Interest Rate Swap
Fair Value Measurements
Net loss		$ (100)

Acquisitions (Details)

Acquisitions (Details) - USD ($) $ in Millions	Feb. 01, 2023	Apr. 01, 2022
Atlantic
Consideration transferred:
Fair value of consideration transferred		$ 48.1
Cash paid at closing		34.1
Notes issued to former owners		$ 5.3
Eldeco Inc
Consideration transferred:
Fair value of consideration transferred	$ 73.9
Cash paid at closing	60.8
Notes issued to former owners	$ 8

Goodwill and Identifiable Int_3

Goodwill and Identifiable Intangible Assets, Net - Changes in Carrying Amount of Goodwill (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2023	Dec. 31, 2022
Changes in the carrying amount of goodwill
Balance at beginning of year	$ 611,789	$ 592,114
Acquisitions and purchase price adjustments (See Note 5)	25,645	19,675
Balance at end of period	637,434	611,789
Mechanical Services Segment
Changes in the carrying amount of goodwill
Balance at beginning of year	363,929	361,320
Acquisitions and purchase price adjustments (See Note 5)		2,609
Balance at end of period	363,929	363,929
Electrical Services Industry
Changes in the carrying amount of goodwill
Balance at beginning of year	247,860	230,794
Acquisitions and purchase price adjustments (See Note 5)	25,645	17,066
Balance at end of period	$ 273,505	$ 247,860

Goodwill and Identifiable Int_4

Goodwill and Identifiable Intangible Assets, Net - Identifiable Intangible Assets, Net (Details) $ in Thousands	Mar. 31, 2023 USD ($)
Future amortization expense of identifiable intangible assets
2023 (remainder of the year)	$ 32,256
2024	37,006
2025	34,525
2026	33,681
2027	31,699
Thereafter	126,903
Total	$ 296,070

Debt Obligations (Details)

Debt Obligations (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Debt Obligations
Other debt	$ 189	$ 205
Total debt	209,229	256,245
Less-current portion	(11,468)	(9,000)
Total long-term portion of debt	197,761	247,245
Revolving credit facility
Debt Obligations
Revolving credit facility	160,000	215,000
Notes to Former Owners
Debt Obligations
Notes to former owners	$ 49,040	$ 41,040

Debt Obligations - Other (Detai

Debt Obligations - Other (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2023 USD ($) item	Dec. 31, 2022 USD ($)	May 25, 2022 USD ($)	May 24, 2022 USD ($)
Revolving credit facility
Debt Obligations
Borrowing capacity			$ 850,000
Outstanding borrowings	$ 160,000
Letters of credit amount outstanding	51,900
Credit available	$ 638,100
Other disclosures
Weighted average interest rate (as a percent)	6.20%	5.70%
Revolving credit facility | Minimum
Debt Instrument, Interest Rate, Effective Percentage [Abstract]
Commitment fees payable on unused portion of the facility (as a percent)	0.15%
Revolving credit facility | Maximum
Debt Instrument, Interest Rate, Effective Percentage [Abstract]
Commitment fees payable on unused portion of the facility (as a percent)	0.25%
Revolving credit facility | Base rate | Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: Less than 1.00
Debt Instrument, Interest Rate, Effective Percentage [Abstract]
Additional per annum interest margin (as a percent)	0%
Revolving credit facility | Base rate | Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 1.00 to 1.75
Debt Instrument, Interest Rate, Effective Percentage [Abstract]
Additional per annum interest margin (as a percent)	0.25%
Revolving credit facility | Base rate | Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 1.75 to 2.50
Debt Instrument, Interest Rate, Effective Percentage [Abstract]
Additional per annum interest margin (as a percent)	0.50%
Revolving credit facility | Base rate | Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 2.50 to 3.00
Debt Instrument, Interest Rate, Effective Percentage [Abstract]
Additional per annum interest margin (as a percent)	0.75%
Revolving credit facility | Base rate | Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 3.00 or Greater
Debt Instrument, Interest Rate, Effective Percentage [Abstract]
Additional per annum interest margin (as a percent)	1%
Amended senior revolving credit facility
Debt Obligations
Borrowing capacity			850,000
Financing and professional cost		$ 2,300
Unamortized costs				$ 1,200
Amended senior revolving credit facility | Maximum
Debt Obligations
Line of credit borrowing capacity accordion option			$ 250,000
Notes to Former Owners
Other disclosures
Cumulative number of companies acquired | item	11
Notes to former owners	$ 49,040	$ 41,040
Letter of Credit
Debt Obligations
Borrowing capacity	$ 175,000
Letter of Credit | Minimum
Debt Instrument, Interest Rate, Effective Percentage [Abstract]
Letter of credit fees (as a percent)	1%
Letter of Credit | Maximum
Debt Instrument, Interest Rate, Effective Percentage [Abstract]
Letter of credit fees (as a percent)	2%
SOFR | Revolving credit facility | Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: Less than 1.00
Debt Instrument, Interest Rate, Effective Percentage [Abstract]
Additional per annum interest margin (as a percent)	1%
SOFR | Revolving credit facility | Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 1.00 to 1.75
Debt Instrument, Interest Rate, Effective Percentage [Abstract]
Additional per annum interest margin (as a percent)	1.25%
SOFR | Revolving credit facility | Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 1.75 to 2.50
Debt Instrument, Interest Rate, Effective Percentage [Abstract]
Additional per annum interest margin (as a percent)	1.50%
SOFR | Revolving credit facility | Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 2.50 to 3.00
Debt Instrument, Interest Rate, Effective Percentage [Abstract]
Additional per annum interest margin (as a percent)	1.75%
SOFR | Revolving credit facility | Consolidated Total Indebtedness to Credit Facility Adjusted EBITDA: 3.00 or Greater
Debt Instrument, Interest Rate, Effective Percentage [Abstract]
Additional per annum interest margin (as a percent)	2%

Debt Obligations - Notes to For

Debt Obligations - Notes to Former Owners (Details) - Notes to Former Owners - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Future principal payments of long-term debt
Notes issued to former owners	$ 49,040	$ 41,040
2023
Future principal payments of long-term debt
Notes issued to former owners	$ 11,400
2023 | Minimum
Future principal payments of long-term debt
Stated interest rate (as a percent)	2.50%
2023 | Maximum
Future principal payments of long-term debt
Stated interest rate (as a percent)	3%
2024
Future principal payments of long-term debt
Notes issued to former owners	$ 4,800
Stated interest rate (as a percent)	2.50%
2025
Future principal payments of long-term debt
Notes issued to former owners	$ 22,215
2025 | Minimum
Future principal payments of long-term debt
Stated interest rate (as a percent)	2.25%
2025 | Maximum
Future principal payments of long-term debt
Stated interest rate (as a percent)	3%
2026
Future principal payments of long-term debt
Notes issued to former owners	$ 10,625
2026 | Minimum
Future principal payments of long-term debt
Stated interest rate (as a percent)	2.50%
2026 | Maximum
Future principal payments of long-term debt
Stated interest rate (as a percent)	3.75%

Leases (Details)

Leases (Details) $ in Millions	3 Months Ended
	Mar. 31, 2023 USD ($) Option	Mar. 31, 2022 USD ($)	Dec. 31, 2022
Leases
Variable lease expense and short-term lease expenses	$ 10.2	$ 4.1
Weighted average discount rate for operating leases	4.50%		4.30%
Operating lease expense	$ 17.3	10.4
Weighted average remaining lease term	7 years 10 months 24 days		8 years 1 month 6 days
Rent paid to related parties	$ 2	$ 1.7
Existence of option to extend	true
Minimum
Leases
Lease term for operating lease	3 years
Number of options to renew | Option	1
Maximum
Leases
Lease term for operating lease	10 years

Leases - Summary of Operating L

Leases - Summary of Operating Lease Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Summary of lease asset and liabilities
Operating lease right-of-use assets	$ 134,755	$ 130,666
Operating lease liabilities:
Other current liabilities	$ 21,487	$ 21,151
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Other Liabilities, Current	Other Liabilities, Current
Long-term operating lease liabilities	$ 115,018	$ 111,744
Total operating lease liabilities	$ 136,505	$ 132,895

Leases - Maturities of Lease Li

Leases - Maturities of Lease Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Maturities of lease liabilities:
2023 (excluding the three months ended March 31, 2023)	$ 20,511
2024	25,536
2025	24,269
2026	20,734
2027	16,543
Thereafter	55,679
Total Lease Payments	163,272
Less-Present Value Discount	(26,767)
Present Value of Operating Lease Liabilities	136,505		$ 132,895
Supplemental information related to leases:
Cash paid for amounts included in the measurement of operating lease liabilities	7,024	$ 6,314
Operating lease right-of-use assets obtained in exchange for lease liabilities	$ 9,446	$ 4,914

Commitments and Contingencies (

Commitments and Contingencies (Details) $ in Millions	3 Months Ended
	Mar. 31, 2023 USD ($)
Dispute With Customer
Commitments and Contingencies
Gain (loss) related to settlement agreements	$ 6.8
Surety | Minimum
Surety
Percentage of business which has required bonds	10%
Surety | Maximum
Surety
Percentage of business which has required bonds	20%
Gross Profit. | Dispute With Customer
Commitments and Contingencies
Gain (loss) related to settlement agreements	$ 6.6
Selling, General and Administrative Expenses | Dispute With Customer
Commitments and Contingencies
Gain (loss) related to settlement agreements	0.7
Interest Income | Dispute With Customer
Commitments and Contingencies
Gain (loss) related to settlement agreements	1.3
Change in Fair Value of Contingent Earn-Out Obligations | Dispute With Customer
Commitments and Contingencies
Gain (loss) related to settlement agreements	$ (1.8)

Stockholders' Equity - Incentiv

Stockholders' Equity - Incentive and Other (Details) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions	3 Months Ended		192 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	May 17, 2022	Mar. 29, 2007
Share Repurchase Program
Share repurchase	$ 3,568	$ 14,097
Anti-dilutive securities excluded from computation of earnings per share amount (in shares)	0	0
Stock Repurchase Program 2007
Share Repurchase Program
Number of shares of outstanding common stock authorized to be acquired under a stock repurchase program	10.9		10.9		1
Additional number of shares authorized for repurchase				0.7
Share repurchase (in shares)			10.1
Average price (in dollars per share)	$ 121.36		$ 24.80
Share repurchase	$ 3,600
Maximum | Stock Repurchase Program 2007
Share Repurchase Program
Share repurchase (in shares)	0.1

Stockholders' Equity - Number o

Stockholders' Equity - Number of Shares (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
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	35,752	35,953
Effect of using weighted average common shares outstanding	60	123
Shares used in computing earnings per share-basic	35,812	36,076
Effect of shares issuable under stock option plans based on the treasury stock method	26	43
Effect of restricted and contingently issuable shares	69	69
Shares used in computing earnings per share-diluted	35,907	36,188

Segment Information (Details)

Segment Information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2023 USD ($) segment	Mar. 31, 2022 USD ($)
Segment Information
Number of reportable segments | segment	2
Revenue	$ 1,174,640	$ 885,216
Gross Profit	205,405	153,144
Operating | Mechanical Services Segment
Segment Information
Revenue	918,615	682,511
Gross Profit	164,067	126,728
Operating | Electrical Services Industry
Segment Information
Revenue	256,025	202,705
Gross Profit	$ 41,338	$ 26,416