Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2018

Summary of Significant Accounting Policies

Schedule of cash paid

Cash paid (in thousands) for:

	Year Ended December 31,
	2018		2017		2016
Interest	$	3,743	$	2,832	$	1,864
Income taxes	$	33,401	$	38,144	$	29,349

Schedule of contracts in progress

Contracts in progress are as follows (in thousands):

	December 31,
	2018		2017
Costs incurred on contracts in progress	$	1,574,460	$	1,288,330
Estimated earnings, net of losses		300,514		253,641
Less—Billings to date		(1,958,567)		(1,617,860)
Less—Unbilled accounts receivable		(37,180)		—
	$	(120,773)	$	(75,889)
Costs and estimated earnings in excess of billings	$	10,213	$	30,116
Billings in excess of costs and estimated earnings		(130,986)		(106,005)
	$	(120,773)	$	(75,889)

Schedule of disaggregation or revenue

Our consolidated 2018 revenue was derived from the following service activities, all of which are in the mechanical services industry, the single industry segment we serve.  See details in the following tables (dollars in thousands):

	Year Ended December 31,
Revenue by Service Provided	2018				2017				2016
HVAC and Plumbing	$	1,976,374	90.5	%	$	1,615,468	90.4	%	$	1,462,980	89.5	%
Building Automation Control Systems		95,093	4.4	%		94,041	5.3	%		90,461	5.5	%
Other		111,412	5.1	%		78,413	4.4	%		80,899	4.9	%
Total	$	2,182,879	100.0	%	$	1,787,922	100.0	%	$	1,634,340	100.0	%
	Year Ended December 31,
Revenue by Type of Customer	2018				2017				2016
Industrial	$	596,557	27.3	%	$	395,362	22.1	%	$	378,499	23.2	%
Education		391,937	18.0	%		351,808	19.7	%		307,195	18.8	%
Office Buildings		288,090	13.2	%		248,604	13.9	%		202,187	12.4	%
Healthcare		319,958	14.7	%		224,643	12.6	%		197,797	12.1	%
Government		143,958	6.6	%		140,843	7.9	%		160,414	9.8	%
Retail, Restaurants and Entertainment		225,348	10.3	%		223,593	12.5	%		196,094	12.0	%
Multi-Family and Residential		136,075	6.2	%		116,844	6.5	%		122,766	7.5	%
Other		80,956	3.7	%		86,225	4.8	%		69,388	4.2	%
Total	$	2,182,879	100.0	%	$	1,787,922	100.0	%	$	1,634,340	100.0	%
	Year Ended December 31,
Revenue by Activity Type	2018				2017				2016
New Construction	$	829,978	38.0	%	$	684,687	38.3	%	$	653,488	40.0	%
Existing Building Construction		796,946	36.5	%		580,737	32.4	%		514,437	31.5	%
Service Projects		206,506	9.5	%		197,703	11.1	%		178,455	10.9	%
Service Calls, Maintenance and Monitoring		349,448	16.0	%		324,795	18.2	%		287,960	17.6	%
Total	$	2,182,879	100.0	%	$	1,787,922	100.0	%	$	1,634,340	100.0	%

Schedule of contract assets and liabilities

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

	Year Ended
	December 31, 2018
	Contract		Contract
	Assets		Liabilities
Balance at beginning of period	$	30,116	$	106,005
Change due to acquisitions		2,833		8,195
Change due to conditional versus unconditional		6,244		—
Reclassified to unbilled accounts receivable		(28,980)		—
Change in timing for performance obligation to be satisfied		—		16,786
Balance at December 31, 2018	$	10,213	$	130,986