Revenue from Contracts with Customers (Tables)

6 Months Ended

Jun. 30, 2021

Revenue from Contract with Customers

Schedule of disaggregation of revenue

See details in the following tables (dollars in thousands):

	Three Months Ended June 30,								Six Months Ended June 30,
Revenue by Service Provided	2021				2020				2021				2020
Mechanical Services	$	611,796	85.7	%	$	626,706	84.3	%	$	1,177,416	85.1	%	$	1,197,457	82.9	%
Electrical Services		102,099	14.3	%		116,762	15.7	%		206,240	14.9	%		246,142	17.1	%
Total	$	713,895	100.0	%	$	743,468	100.0	%	$	1,383,656	100.0	%	$	1,443,599	100.0	%

	Three Months Ended June 30,								Six Months Ended June 30,
Revenue by Type of Customer	2021				2020				2021				2020
Industrial	$	311,075	43.6	%	$	300,870	40.5	%	$	580,658	42.0	%	$	576,068	39.9	%
Education		92,381	12.9	%		130,004	17.5	%		184,838	13.4	%		239,588	16.6	%
Office Buildings		73,014	10.2	%		75,594	10.2	%		152,010	11.0	%		151,166	10.5	%
Healthcare		96,004	13.4	%		96,050	12.9	%		191,095	13.8	%		195,309	13.5	%
Government		42,506	6.0	%		39,832	5.4	%		85,671	6.2	%		78,813	5.5	%
Retail, Restaurants and Entertainment		48,933	6.9	%		64,628	8.7	%		93,509	6.7	%		125,831	8.7	%
Multi-Family and Residential		28,341	4.0	%		20,555	2.8	%		53,001	3.8	%		39,286	2.7	%
Other		21,641	3.0	%		15,935	2.0	%		42,874	3.1	%		37,538	2.6	%
Total	$	713,895	100.0	%	$	743,468	100.0	%	$	1,383,656	100.0	%	$	1,443,599	100.0	%
	Three Months Ended June 30,								Six Months Ended June 30,
Revenue by Activity Type	2021				2020				2021				2020
New Construction	$	329,890	46.2	%	$	377,433	50.8	%	$	631,951	45.7	%	$	724,833	50.2	%
Existing Building Construction		215,317	30.2	%		225,103	30.3	%		431,918	31.2	%		432,269	29.9	%
Service Projects		66,263	9.3	%		58,378	7.8	%		126,323	9.1	%		110,026	7.6	%
Service Calls, Maintenance and Monitoring		102,425	14.3	%		82,554	11.1	%		193,464	14.0	%		176,471	12.3	%
Total	$	713,895	100.0	%	$	743,468	100.0	%	$	1,383,656	100.0	%	$	1,443,599	100.0	%

Schedule of contract assets and liabilities

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

	Six Months Ended June 30,					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		(6,170)		27,510		6,456		19,434
Balance at end of period	$	12,969	$	255,357	$	18,622	$	226,237