Income Taxes - Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Deferred benefit
Federal	$ (14,035)	$ (9,602)	$ (5,651)
State	(2,443)	(1,742)	(449)
Deferred Foreign Income Tax Expense (Benefit)	(114)	0	0
Total deferred benefit	(16,592)	(11,344)	(6,100)
Valuation allowance	16,592	11,344	6,100
Total income tax provision	$ 0	$ 0	$ 0