Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Loss before Income Taxes
United States	$ (67,402)	$ (84,595)	$ (61,733)
International	1,204	965	361
Loss before income taxes	(66,198)	(83,630)	(61,372)
Income tax expense, current:
State	22	26	25
Foreign	960	826	492
Total current income tax expense	$ 982	$ 852	$ 517