Goodwill and Intangible Assets - Goodwill / Tradename (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill, beginning balance	$ 166,951	$ 170,153
Goodwill, divestitures	(14,317)
Goodwill, impairment		(4,443)
Goodwill, foreign currency translation	(263)	1,241
Goodwill, ending balance	152,371	166,951
Tradename, beginning balance	19,691	22,042
Tradename, divestitures	(1,340)
Tradename, impairment		(2,725)
Tradename, foreign currency translation	(51)	374
Tradename, ending balance	$ 18,300	$ 19,691