Income Taxes - Significant Components of the Provision (Benefit) for Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current:
Federal	$ 6,039	$ 16,346	$ 13,594
State	1,263	1,534	996
Foreign	656	1,050	0
Total current	7,958	18,930	14,590
Deferred:
Federal	4,539	(4,145)	288
State	(1,631)	(977)	984
Foreign	(78)	(45)	(278)
Total deferred	2,830	(5,167)	994
Tax provision recorded as an increase (decrease) in liability for unrecorded tax benefits	(234)	437	(156)
Provision for income taxes	$ 10,554	$ 14,200	$ 15,428