Income Taxes - Income Tax Expense (Benefit) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Current
U.S.	$ 0	$ 0
State	0	0
Foreign	331	13
Total current income tax expense	331	13
Deferred
U.S.	0	0
State	0	0
Foreign	(554)	(39)
Total deferred income tax (benefit)	(554)	(39)
Total income tax (benefit)	$ (223)	$ (26)