Business Combinations - Estimates of Acquired Intangible Assets (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Customer Relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Fair Value	$ 12,862	$ 29,958
Weighted Avg Estimated Useful Life (yrs)	9 years	8 years
Trademarks and Trade Names [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Fair Value	$ 6,116	$ 12,882
Weighted Avg Estimated Useful Life (yrs)	15 years	15 years
Covenants Not-to-compete [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Fair Value	$ 2,314	$ 3,818
Weighted Avg Estimated Useful Life (yrs)	5 years	5 years