Stockholders' Equity - Common Stock Warrants (Details) - Common stock warrants	6 Months Ended
	Jun. 30, 2020 $ / shares shares
Common Stock Warrants
Warrants Outstanding (in shares) | shares	6,193,749
Weighted average life (in years)	3 years 2 months 5 days
Weighted Average
Common Stock Warrants
Exercise Price (in dollars per share) | $ / shares	$ 10.19
Warrants Issued in 2014
Common Stock Warrants
Warrants Outstanding (in shares) | shares	1,227
Exercise Price (in dollars per share) | $ / shares	$ 122.12
Warrants Issued in 2015
Common Stock Warrants
Warrants Outstanding (in shares) | shares	1,227
Exercise Price (in dollars per share) | $ / shares	$ 122.12
Warrants Issued in 2018
Common Stock Warrants
Warrants Outstanding (in shares) | shares	4,199,995
Exercise Price (in dollars per share) | $ / shares	$ 12.00
Warrants Issued in 2019
Common Stock Warrants
Warrants Outstanding (in shares) | shares	1,991,300
Exercise Price (in dollars per share) | $ / shares	$ 6.25