Goodwill and Intangible Assets - Intangible Assets and Accumulated Amortization Balances (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 166,121	$ 140,429
Accumulated Amortization	(80,173)	(69,727)
Net Carrying Amount	85,948	70,702
Customer relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	135,482	115,285
Accumulated Amortization	(70,075)	(61,375)
Net Carrying Amount	65,407	53,910
Developed technology [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	8,971	8,854
Accumulated Amortization	(8,449)	(7,673)
Net Carrying Amount	522	1,181
Other [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	21,668	16,290
Accumulated Amortization	(1,649)	(679)
Net Carrying Amount	$ 20,019	$ 15,611