Goodwill and Intangible Assets - Goodwill / Tradenames (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill, beginning balance	$ 152,156	$ 166,951
Goodwill, divestitures		(14,317)
Goodwill, foreign currency translation	(90)	(478)
Goodwill, ending balance	152,066	152,156
Tradenames, beginning balance	18,258	19,691
Tradenames, transfers to finite life classification	3,904
Tradenames, divestitures		(1,340)
Tradenames, foreign currency translation	(40)	(93)
Tradenames, ending balance	$ 14,314	$ 18,258