Revenue from Contracts with Customers (Tables)

12 Months Ended

Dec. 31, 2021

Revenue from Contract with Customers

Schedule of contracts in progress

Contracts in progress are as follows (in thousands):

	December 31,
	2021		2020
Costs incurred on contracts in progress	$	3,723,715	$	3,103,580
Estimated earnings, net of losses		589,286		548,435
Less—Billings to date		(4,527,801)		(3,813,171)
Less—Unbilled accounts receivable		(61,881)		(45,596)
Less—Unbilled accounts receivable credit allowance		(715)		(784)
	$	(277,396)	$	(207,536)
Costs and estimated earnings in excess of billings	$	29,900	$	18,622
Plus—Costs and estimated earnings in excess of billings credit allowance		84		79
Billings in excess of costs and estimated earnings		(307,380)		(226,237)
	$	(277,396)	$	(207,536)

Schedule of disaggregation of revenue

Our consolidated 2021 revenue was derived from contracts to provide service activities in the mechanical and electrical services segments we serve. Refer to Note 16 “Segment Information” for additional information on our reportable segments. We disaggregate our revenue from contracts with customers by activity, customer type and service provided, as we believe it best depicts how the nature, amount, timing and uncertainty of our revenue and cash flows are affected by economic factors. See details in the following tables (dollars in thousands):

	Year Ended December 31,
Revenue by Service Provided	2021				2020				2019
Mechanical Services	$	2,542,623	82.7	%	$	2,430,632	85.1	%	$	2,272,031	86.9	%
Electrical Services		531,013	17.3	%		426,027	14.9	%		343,246	13.1	%
Total	$	3,073,636	100.0	%	$	2,856,659	100.0	%	$	2,615,277	100.0	%
	Year Ended December 31,
Revenue by Type of Customer	2021				2020				2019
Industrial	$	1,356,688	44.1	%	$	1,112,075	38.9	%	$	886,668	33.9	%
Education		390,251	12.7	%		487,922	17.1	%		412,318	15.8	%
Office Buildings		308,799	10.1	%		319,426	11.2	%		348,640	13.3	%
Healthcare		417,901	13.6	%		371,105	13.0	%		358,155	13.7	%
Government		174,813	5.7	%		163,717	5.7	%		162,507	6.2	%
Retail, Restaurants and Entertainment		213,386	6.9	%		239,541	8.4	%		248,083	9.5	%
Multi-Family and Residential		112,779	3.7	%		86,799	3.0	%		104,693	4.0	%
Other		99,019	3.2	%		76,074	2.7	%		94,213	3.6	%
Total	$	3,073,636	100.0	%	$	2,856,659	100.0	%	$	2,615,277	100.0	%
	Year Ended December 31,
Revenue by Activity Type	2021				2020				2019
New Construction	$	1,421,784	46.3	%	$	1,333,739	46.7	%	$	1,201,122	45.9	%
Existing Building Construction		963,461	31.3	%		910,807	31.9	%		793,159	30.3	%
Service Projects		278,582	9.1	%		241,402	8.4	%		231,228	8.9	%
Service Calls, Maintenance and Monitoring		409,809	13.3	%		370,711	13.0	%		389,768	14.9	%
Total	$	3,073,636	100.0	%	$	2,856,659	100.0	%	$	2,615,277	100.0	%

Schedule of contract assets and liabilities

	Year Ended December 31,					Year Ended December 31,
	2021				2020
	Contract		Contract		Contract		Contract
	Assets		Liabilities		Assets		Liabilities
Balance at beginning of period	$	18,622	$	226,237	$	2,736	$	166,918
Change due to acquisitions / disposals		10,356		36,523		9,509		39,885
Change related to credit allowance		(5)		—		(79)		—
Other changes in the period		927		44,620		6,456		19,434
Balance at end of period	$	29,900	$	307,380	$	18,622	$	226,237