Acquisition - Estimated Fair Values of Identifiable Intangible Assets and Related Weighted Average Amortization (Detail) - Jun. 30, 2015 - Acquisitions [Member] - USD ($) $ in Thousands	Total
Finite-Lived Intangible Assets [Line Items]
Estimated Fair Value at Acquisition Date	$ 14,796
Weighted Average Amortization Period at Acquisition Date	13 years 1 month 6 days
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Fair Value at Acquisition Date	$ 9,985
Weighted Average Amortization Period at Acquisition Date	17 years 6 months
Backlog [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Fair Value at Acquisition Date	$ 1,327
Weighted Average Amortization Period at Acquisition Date	1 year 3 months 18 days
Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Fair Value at Acquisition Date	$ 2,374
Weighted Average Amortization Period at Acquisition Date	4 years 8 months 12 days
Non-compete Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Fair Value at Acquisition Date	$ 1,110
Weighted Average Amortization Period at Acquisition Date	5 years