Fair Value Measurements - Fair Value Hierarchy (Details) - Recurring - Measured at fair value - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Assets
Cash and cash equivalents	$ 12,925	$ 17,515
Total Assets	12,925	17,515
Liabilities
Warrant liability	15,716	6,034
Derivative liability	1,194	1,735
Total Liabilities	16,910	7,769
Quoted prices in active markets (Level 1)
Assets
Cash and cash equivalents	12,925	17,515
Total Assets	12,925	17,515
Liabilities
Warrant liability	0	0
Derivative liability	0	0
Total Liabilities	0	0
Fair Value, Inputs, Level 2 [Member]
Assets
Cash and cash equivalents	0	0
Total Assets	0	0
Liabilities
Warrant liability	0	0
Derivative liability	0	0
Total Liabilities	0	0
Significant unobservable inputs (Level 3)
Assets
Cash and cash equivalents	0	0
Total Assets	0	0
Liabilities
Warrant liability	15,716	6,034
Derivative liability	1,194	1,735
Total Liabilities	$ 16,910	$ 7,769