Income Taxes - Summary of Income Tax Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current:
Federal	$ 0	$ 0	$ 0
State	5	5	(19)
Foreign	63	44	172
Total current	68	49	153
Deferred:
Federal	0	0	0
State	0	0	0
Foreign	0	0	0
Total deferred	0	0	0
Total provision	$ 68	$ 49	$ 153