Income Taxes - Provision (Benefit) for Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Document Fiscal Year Focus	2017
Current provision (benefit), federal	$ 2,954	$ (4)	$ (153)
Deferred provision (benefit), federal	7,716	(1,801)	6,077
Total provision (benefit), federal	10,670	(1,805)	5,924
Current provision (benefit), state and local	362	(27)	380
Deferred provision (benefit), state and local	(371)	1,021	389
Total provision (benefit), state and local	(9)	994	769
Current provision (benefit), foreign	4,042	2,605	1,374
Deferred provision (benefit), foreign	647	(1,745)	1,691
Total provision (benefit), foreign	4,689	860	3,065
Current provision (benefit)	7,358	2,574	1,601
Deferred provision (benefit)	7,992	(2,525)	8,157
Provision for income taxes	$ 15,350	$ 49	$ 9,758