Goodwill and Identifiable Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2015

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, 2015 and 2014 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, 2013	$	3,823	$	217,255	$	229,204		$	384,543	$	834,825
Acquisitions, sales and purchase price adjustments	—		—		(819		)	96		(723		)
Balance at December 31, 2014	3,823		217,255		228,385			384,639		834,102
Acquisitions, sales and purchase price adjustments	—		8,816		252			—		9,068
Balance at December 31, 2015	$	3,823	$	226,071	$	228,637		$	384,639	$	843,170

Schedule of Intangible Assets

Identifiable intangible assets as of December 31, 2015 and 2014 consist of the following (in thousands):

	December 31, 2015
	Gross Carrying Amount		Accumulated Amortization			Accumulated Impairment Charge			Total
Contract backlog	$	47,745	$	(47,745	)	$	—		$	—
Developed technology/Vendor network	95,661		(40,482		)	—			55,179
Customer relationships	430,356		(141,695		)	(4,834		)	283,827
Non-competition agreements	10,220		(9,832		)	—			388
Trade names (amortized)	21,248		(12,410		)	—			8,838
Trade names (unamortized)	174,039		—			(49,437		)	124,602
Total	$	779,269	$	(252,164	)	$	(54,271	)	$	472,834

	December 31, 2014
	Gross Carrying Amount		Accumulated Amortization			Accumulated Impairment Charge			Total
Contract backlog	$	47,620	$	(47,620	)	$	—		$	—
Developed technology/Vendor network	95,661		(35,347		)	—			60,314
Customer relationships	425,873		(112,457		)	(4,834		)	308,582
Non-competition agreements	9,980		(9,330		)	—			650
Trade names (amortized)	21,248		(9,515		)	—			11,733
Trade names (unamortized)	170,218		—			(49,437		)	120,781
Total	$	770,600	$	(214,269	)	$	(54,271	)	$	502,060

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):

2016	$	37,380
2017	35,003
2018	32,835
2019	30,853
2020	30,671
Thereafter	181,490
	$	348,232