Fair Value Measurements - Valuation Technique (Details)	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Derivative Liabilities | Expected dividend yield
Valuation technique for assets and liabilities measured and recorded at fair value
Equity Instrument, Measurement Input	0
Minimum | Warrants | Risk free interest rate
Valuation technique for assets and liabilities measured and recorded at fair value
Equity Instrument, Measurement Input	1.89	2.72
Minimum | Warrants | Volatility
Valuation technique for assets and liabilities measured and recorded at fair value
Equity Instrument, Measurement Input	85.00	85.00
Minimum | Warrants | Expected average term
Valuation technique for assets and liabilities measured and recorded at fair value
Equity Instrument Expected average term	7 years 9 months 4 days	8 years 9 months 4 days
Minimum | Derivative Liabilities | Risk free interest rate
Valuation technique for assets and liabilities measured and recorded at fair value
Derivative Liability, Measurement Input		1.64
Minimum | Derivative Liabilities | Volatility
Valuation technique for assets and liabilities measured and recorded at fair value
Derivative Liability, Measurement Input		18.40
Minimum | Derivative Liabilities | Expected average term
Valuation technique for assets and liabilities measured and recorded at fair value
Derivative Liability, Expected average term	3 months 11 days	4 days
Maximum | Warrants | Risk free interest rate
Valuation technique for assets and liabilities measured and recorded at fair value
Equity Instrument, Measurement Input	2.33	2.80
Maximum | Warrants | Expected average term
Valuation technique for assets and liabilities measured and recorded at fair value
Equity Instrument Expected average term	8 years 3 months 18 days	9 years 3 months 18 days
Maximum | Derivative Liabilities | Risk free interest rate
Valuation technique for assets and liabilities measured and recorded at fair value
Derivative Liability, Measurement Input		2.43
Maximum | Derivative Liabilities | Volatility
Valuation technique for assets and liabilities measured and recorded at fair value
Derivative Liability, Measurement Input		81.69
Maximum | Derivative Liabilities | Expected average term
Valuation technique for assets and liabilities measured and recorded at fair value
Derivative Liability, Expected average term	6 months 11 days	1 year 6 months 11 days