Income Taxes - Components of Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current provision (benefit):
Federal	$ 0	$ 0	$ 0
State	5	5	5
Foreign	(14)	(13)	(371)
Total current provision (benefit)	(9)	(8)	(366)
Deferred provision (benefit):
Federal	0	(293)	0
State	0	(21)	0
Foreign	(31)	(16)	110
Total deferred provision (benefit)	(31)	(330)	110
Total benefit from income taxes	$ (40)	$ (338)	$ (256)