Acquisition - Estimated Fair Values of Identifiable Intangible Assets and Related Weighted Average Amortization (Detail) (Acquisitions [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Estimated Fair Value at Acquisition Date	$ 96,302
Weighted Average Amortization Period at Acquisition Date	9 years 8 months 12 days
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Fair Value at Acquisition Date	65,243
Weighted Average Amortization Period at Acquisition Date	12 years 2 months 12 days
Backlog [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Fair Value at Acquisition Date	17,059
Weighted Average Amortization Period at Acquisition Date	1 year 1 month 6 days
Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Fair Value at Acquisition Date	10,436
Weighted Average Amortization Period at Acquisition Date	9 years 8 months 12 days
Non-compete Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Fair Value at Acquisition Date	3,160
Weighted Average Amortization Period at Acquisition Date	5 years
Patented Rights and Developed Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Fair Value at Acquisition Date	$ 404
Weighted Average Amortization Period at Acquisition Date	10 years