Stockholders' Equity - Common Stock Warrants (Details) - Warrants for the purchase of common stock	9 Months Ended
	Sep. 30, 2021 $ / shares shares
Common Stock Warrants
Warrants Outstanding (in shares) | shares	1,530,380
Weighted Average
Common Stock Warrants
Exercise Price (in dollars per share) | $ / shares	$ 41.84
Weighted average life (in years)	4 years 3 months 18 days
Warrants Issued in 2015
Common Stock Warrants
Warrants Outstanding (in shares) | shares	204
Exercise Price (in dollars per share) | $ / shares	$ 732.72
Warrants Issued in 2018
Common Stock Warrants
Warrants Outstanding (in shares) | shares	699,962
Exercise Price (in dollars per share) | $ / shares	$ 72.00
Warrants Issued in 2019
Common Stock Warrants
Warrants Outstanding (in shares) | shares	331,858
Exercise Price (in dollars per share) | $ / shares	$ 37.50
Warrants Issued In 2021
Common Stock Warrants
Warrants Outstanding (in shares) | shares	498,356
Exercise Price (in dollars per share) | $ / shares	$ 2.10