Income Taxes - Components of the Provision for Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current:
Federal	$ 80	$ (9)	$ 117
State	11	14	3
Foreign	0	0	0
Total current	91	5	120
Deferred:
Foreign	0	0	531
Total deferred	0	0	531
Provision for income taxes	$ 91	$ 5	$ 651