Provision for Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current:
Federal	$ 2,124	$ 5,136	$ 573
State	1,347	(122)	417
Foreign	570	655	991
Deferred:
Federal	160	(1,345)	(319)
State	242	1,216	347
Total income tax expense (benefit)	$ 4,443	$ 5,540	$ 2,009