Goodwill and Identifiable Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Goodwill

The changes in the carrying amount of goodwill by reportable segments during the years ended December 31, 2018 and 2017 were as follows (in thousands):

	United States electrical construction and facilities services segment		United States mechanical construction and facilities services segment			United States building services segment		United States industrial services segment			Total
Balance at December 31, 2016	$	123,600	$	226,596		$	244,793	$	384,639		$	979,628
Acquisitions, sales and purchase price adjustments	2,107		30,969			9,640		—			42,716
Intersegment transfers	—		(1,300		)	1,300		—			—
Impairment	—		—			—		(57,451		)	(57,451		)
Balance at December 31, 2017	125,707		256,265			255,733		327,188			964,893
Acquisitions, sales and purchase price adjustments	7,500		56			18,438		—			25,994
Balance at December 31, 2018	$	133,207	$	256,321		$	274,171	$	327,188		$	990,887

Schedule of Intangible Assets

Identifiable intangible assets as of December 31, 2018 and 2017 consist of the following (in thousands):

	December 31, 2018
	Gross Carrying Amount		Accumulated Amortization			Accumulated Impairment Charge			Total
Contract backlog	$	58,945	$	(56,812	)	$	—		$	2,133
Developed technology/Vendor network	95,661		(55,318		)	—			40,343
Customer relationships	522,855		(240,073		)	(4,834		)	277,948
Non-competition agreements	10,220		(10,220		)	—			—
Trade names (amortized)	31,148		(20,893		)	—			10,255
Trade names (unamortized)	209,840		—			(52,233		)	157,607
Total	$	928,669	$	(383,316	)	$	(57,067	)	$	488,286

	December 31, 2017
	Gross Carrying Amount		Accumulated Amortization			Accumulated Impairment Charge			Total
Contract backlog	$	55,545	$	(55,229	)	$	—		$	316
Developed technology/Vendor network	95,661		(50,479		)	—			45,182
Customer relationships	500,756		(206,319		)	(4,834		)	289,603
Non-competition agreements	10,220		(10,178		)	—			42
Trade names (amortized)	32,848		(19,461		)	—			13,387
Trade names (unamortized)	198,739		—			(52,233		)	146,506
Total	$	893,769	$	(341,666	)	$	(57,067	)	$	495,036

Schedule of Estimated Future Amortization Expense

The following table presents the estimated future amortization expense of identifiable intangible assets in the following years (in thousands):

2019	$	42,315
2020	40,000
2021	39,207
2022	37,003
2023	36,065
Thereafter	136,089
	$	330,679