Intangible Assets (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Amortization of Intangible Assets	$ 1,100	$ 1,000	$ 3,200	$ 3,000
Historical Cost	44,861		44,861		$ 44,861
Accumulated Amortization	(28,581)		(28,581)		(24,871)
Net Balance	16,280		$ 16,280		$ 19,990
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Useful Life			9 years		9 years
Historical Cost	41,001		$ 41,001		$ 41,001
Accumulated Amortization	(26,195)		(26,195)		(22,778)
Net Balance	14,806		$ 14,806		$ 18,223
Tradenames and trademarks
Finite-Lived Intangible Assets [Line Items]
Useful Life			10 years		10 years
Historical Cost	3,286		$ 3,286		$ 3,286
Accumulated Amortization	(1,889)		(1,889)		(1,643)
Net Balance	1,397		$ 1,397		$ 1,643
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Useful Life			5 years		5 years
Historical Cost	574		$ 574		$ 574
Accumulated Amortization	(497)		(497)		(450)
Net Balance	$ 77		$ 77		$ 124