Goodwill and Intangibles - Carrying Amount of Goodwill by Reportable Operating Segment (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Line Items]
Goodwill, Beginning Balance		$ 167,441	$ 149,219
Acquisitions		414	10,147
Goodwill, Other Increase (Decrease)			9,741
Foreign exchange translation		3,997	(1,666)
Goodwill, Ending Balance		171,852	167,441
North America [Member]
Goodwill [Line Items]
Goodwill, Beginning Balance		121,996	114,109
Acquisitions	$ 7,175	178	7,175
Goodwill, Other Increase (Decrease)			0
Foreign exchange translation		221	712
Goodwill, Ending Balance		122,395	121,996
Europe [Member]
Goodwill [Line Items]
Goodwill, Beginning Balance		10,753	11,056
Acquisitions		236	0
Goodwill, Other Increase (Decrease)			0
Foreign exchange translation		1,465	(303)
Goodwill, Ending Balance		12,454	10,753
Asia Pacific [Member]
Goodwill [Line Items]
Goodwill, Beginning Balance		34,692	24,054
Acquisitions		0	2,972
Goodwill, Other Increase (Decrease)			9,741
Foreign exchange translation		2,311	(2,075)
Goodwill, Ending Balance		$ 37,003	$ 34,692