Revenue from Contracts with Customers (Tables)

3 Months Ended

Mar. 31, 2021

Revenue from Contract 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	2021				2020
Mechanical Services	$	565,620	84.5	%	$	570,751	81.5	%
Electrical Services		104,141	15.5	%		129,380	18.5	%
Total	$	669,761	100.0	%	$	700,131	100.0	%

	Three Months Ended March 31,
Revenue by Type of Customer	2021				2020
Industrial	$	269,583	40.3	%	$	275,198	39.3	%
Education		92,457	13.8	%		109,584	15.7	%
Office Buildings		78,996	11.8	%		75,572	10.8	%
Healthcare		95,091	14.2	%		99,259	14.2	%
Government		43,165	6.4	%		38,981	5.6	%
Retail, Restaurants and Entertainment		44,576	6.7	%		61,203	8.7	%
Multi-Family and Residential		24,660	3.7	%		18,731	2.7	%
Other		21,233	3.1	%		21,603	3.0	%
Total	$	669,761	100.0	%	$	700,131	100.0	%
	Three Months Ended March 31,
Revenue by Activity Type	2021				2020
New Construction	$	302,061	45.1	%	$	347,400	49.6	%
Existing Building Construction		216,601	32.3	%		207,166	29.6	%
Service Projects		60,060	9.0	%		51,648	7.4	%
Service Calls, Maintenance and Monitoring		91,039	13.6	%		93,917	13.4	%
Total	$	669,761	100.0	%	$	700,131	100.0	%

Schedule of contract assets and liabilities

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

	Three Months Ended March 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		472		1,610		9,509		39,885
Change related to credit allowance		45		—		(79)		—
Other changes in the period		(8,972)		20,550		6,456		19,434
Balance at end of period	$	10,167	$	248,397	$	18,622	$	226,237