Goodwill and Intangible Assets - Goodwill / Tradename (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill, beginning balance	$ 167,547	$ 134,062
Goodwill, acquisitions and related adjustments	65,687	34,638
Goodwill, foreign currency translation	(994)	(1,153)
Goodwill, ending balance	232,240	167,547
Tradename, beginning balance	19,766	18,419
Tradename, acquisitions and related adjustments	10,750	1,730
Tradename, foreign currency translation	(267)	(383)
Tradename, ending balance	$ 30,249	$ 19,766