Preferred Stock and Common Stock Warrants - Warrants (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) $ / shares
Warrants
Gain (loss) recognized on revalued warrants | $	$ 164
Series A Warrants | HGC
Warrants
Basis of acquired diluted common stock - warrants rights (as a percent)	0.50%
Strike price of warrants (in dollars per share)	$ 0.01
Series A Warrants | Fund Purchaser
Warrants
Basis of acquired diluted common stock - warrants rights (as a percent)	0.21%
Strike price of warrants (in dollars per share)	$ 0.01
Series B Warrants | Series B Convertible Preferred stock
Warrants
Basis of acquired diluted common stock - warrants rights (as a percent)	0.42%
Strike price of warrants (in dollars per share)	$ 0.01
Common Stock Warrants
Warrants
Term of warrants (in years)	3 years
Number of trading days to exercise prior to expiration term	60 days
Number of consecutive trading days to exercise warrants prior to expiration term	90 days
Minimum conversion price percentage	175.00%
Gain (loss) recognized on revalued warrants | $	$ 164