Income Taxes - Components of Provision for Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current:
Federal	$ 11,526	$ 15,376	$ 18,291
State	956	1,513	1,204
Foreign	2,425	2,104	1,684
Total Current	14,907	18,993	21,179
Deferred:
Federal	(2,472)	(594)	1,583
State	256	601	1,696
Foreign	(717)	(1,179)	306
Total Deferred	(2,933)	(1,172)	3,585
Provision for income taxes	$ 11,974	$ 17,821	$ 24,764