Goodwill and Other Intangible Assets - Other Intangible Assets (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Finite And Indefinite Lived Intangible Assets [Line Items]
Intangible assets subject to amortization	$ 511,951	$ 426,732
Accumulated Amortization	(255,858)	(223,355)
Intangible Assets, Net	256,093	203,377
Remaining Weighted Average Amortization Period in Years	11 years
Customer Relationships [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Intangible assets subject to amortization	257,380	199,224
Accumulated Amortization	(74,289)	(59,417)
Intangible Assets, Net	183,091	139,807
Remaining Weighted Average Amortization Period in Years	10 years 2 months 12 days
Backlog [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Intangible assets subject to amortization	151,404	136,831
Accumulated Amortization	(138,460)	(127,233)
Intangible Assets, Net	12,944	9,598
Remaining Weighted Average Amortization Period in Years	1 year 3 months 18 days
Trade Names [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Intangible assets subject to amortization	49,664	40,342
Accumulated Amortization	(6,278)	(4,228)
Intangible Assets, Net	43,386	36,114
Remaining Weighted Average Amortization Period in Years	20 years
Non-compete Agreements [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Intangible assets subject to amortization	31,430	28,895
Accumulated Amortization	(25,136)	(22,860)
Intangible Assets, Net	6,294	6,035
Remaining Weighted Average Amortization Period in Years	3 years 4 months 24 days
Patented Rights and Developed Technology [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Intangible assets subject to amortization	22,073	21,440
Accumulated Amortization	(11,695)	(9,617)
Intangible Assets, Net	$ 10,378	$ 11,823
Remaining Weighted Average Amortization Period in Years	4 years 7 months 6 days