Income Taxes - Income Tax (Benefit) Provision (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current:
Federal	$ (4,698)	$ (1,574)	$ 4,577
State	(440)	465	378
Foreign	606	414	(20)
Current income tax (benefit) provision	(4,532)	(695)	4,935
Deferred:
Federal	1,259	(2,688)	(2,203)
State	(112)	(1,838)	197
Foreign	1,876	(2,472)	(296)
Increase in valuation allowance	154	30,405	0
Deferred income tax provision (benefit)	3,177	23,407	(2,302)
Total income tax (benefit) provision	$ (1,355)	$ 22,712	$ 2,633