Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - Fair Value, Measurements, Recurring - Estimate of Fair Value Measurement - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 17,515	$ 29,268
Total Assets	17,515	29,268
Warrant liability	6,034	8,275
Derivative liability	1,735	0
Total Liabilities	7,769	8,275
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	17,515	29,268
Total Assets	17,515	29,268
Warrant liability	0	0
Derivative liability	0	0
Total Liabilities	0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Total Assets	0	0
Warrant liability	0	0
Derivative liability	0	0
Total Liabilities	0	0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Total Assets	0	0
Warrant liability	6,034	8,275
Derivative liability	1,735	0
Total Liabilities	$ 7,769	$ 8,275