Stock Warrants - Warrant liability (Details) - $ / shares		1 Months Ended	12 Months Ended
	Oct. 10, 2014	Nov. 18, 2016	Dec. 31, 2018	Dec. 31, 2017
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Closing stock price	$ 61.25		$ 0.56	$ 17.85
Expected dividends	0.00%		0.00%	0.00%
Expected volatility	95.00%		110.00%	80.00%
Risk free interest rate	1.39%		2.60%	1.86%
Expected life of warrant	5 years		9 months 15 days	1 year 9 months 15 days
Series A Warrants [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Closing stock price		$ 31.15	$ 0.56	$ 17.85
Expected dividends		0.00%	0.00%	0.00%
Expected volatility		85.00%	92.50%	80.00%
Risk free interest rate		1.58%	2.50%	1.97%
Expected life of warrant		4 years	1 year 10 months 24 days	2 years 10 months 24 days