Income Taxes - Components of Income Tax (Benefit) Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current:
Federal	$ 0	$ 0	$ 0
State	1	1	1
Current Income Tax Expense (Benefit), total	1	1	1
Deferred:
Federal	(5)	(17)	0
State	0	(2)	0
Deferred Income Tax Expense (Benefit), total	(5)	(19)	0
Income tax (benefit) expense	$ (4)	$ (18)	$ 1