Fair Value Measurement - Instruments Measured on a Non-recurring Basis (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2017 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrant, fair value disclosure	$ 2,100
Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrant, fair value disclosure	2,140
Fair Value, Measurements, Nonrecurring | Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrant, fair value disclosure	0
Fair Value, Measurements, Nonrecurring | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrant, fair value disclosure	0
Fair Value, Measurements, Nonrecurring | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrant, fair value disclosure	2,140
Total Gains (Losses)	$ 0