Goodwill and Identifiable Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2014

Goodwill and Intangible Assets Disclosure [Abstract]

The changes in the carrying amount of goodwill by reportable segments during the years ended December 31, 2014 and 2013 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, 2012	$	3,823	$	201,150	$	244,787		$	116,828	$	566,588
Acquisitions, sales and purchase price adjustments	—		522		—			267,715		268,237
Transfers	—		15,583		(15,583		)	—		—
Balance at December 31, 2013	3,823		217,255		229,204			384,543		834,825
Acquisitions, sales and purchase price adjustments	—		—		(819		)	96		(723		)
Transfers	—		—		—			—		—
Balance at December 31, 2014	$	3,823	$	217,255	$	228,385		$	384,639	$	834,102

Schedule of Intangible Assets

Identifiable intangible assets as of December 31, 2014 and 2013 consist of the following (in thousands):



	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



	December 31, 2013
	Gross Carrying Amount		Accumulated Amortization			Accumulated Impairment Charge			Total
Contract backlog	$	47,620	$	(47,583	)	$	—		$	37
Developed technology/Vendor network	95,661		(30,212		)	—			65,449
Customer relationships	425,873		(83,391		)	(4,834		)	337,648
Non-competition agreements	9,980		(8,498		)	—			1,482
Trade names (amortized)	21,248		(6,619		)	—			14,629
Trade names (unamortized)	170,218		—			(47,966		)	122,252
Total	$	770,600	$	(176,303	)	$	(52,800	)	$	541,497

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):



2015	$	37,565
2016	36,502
2017	34,195
2018	32,070
2019	30,105
Thereafter	210,842
	$	381,279