Provision Benefit for Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Foreign	$ 147	$ 147	$ 168
Federal	0	0	0
State			1
Total current	147	147	169
Foreign	0	0	0
Federal	28	(3,750)	22
State		(68)	4
Total deferred	28	(3,818)	26
Provision (benefit) for income taxes	$ 175	$ (3,671)	$ 195