Stockholders' Equity - Common Stock Warrants (Details) - $ / shares	Mar. 31, 2022	Dec. 31, 2021
Class of Warrant or Right
Number of Shares	8,732,230	8,732,230
Equity Classified Warrants
Class of Warrant or Right
Number of Shares	8,732,230	8,732,230
May 2013 Warrants
Class of Warrant or Right
Number of Shares	15,437	15,437
Weighted-Average Exercise Price	$ 0.08
September 2013 Warrants
Class of Warrant or Right
Number of Shares	4,096	4,096
Weighted-Average Exercise Price	$ 0.08
February 2014 Warrants
Class of Warrant or Right
Number of Shares	2,171	2,171
Weighted-Average Exercise Price	$ 0.08
April 2020 Private Placement first closing warrants
Class of Warrant or Right
Number of Shares	3,039,514	3,039,514
Weighted-Average Exercise Price	$ 2.28
April 2020 Private Placement second closing warrants
Class of Warrant or Right
Number of Shares	1,373,626	1,373,626
Weighted-Average Exercise Price	$ 2.71
April 2020 Private Placement second closing warrants
Class of Warrant or Right
Number of Shares	1,143,428	1,143,428
Weighted-Average Exercise Price	$ 0.01
July 2020 Private Placement first closing warrants
Class of Warrant or Right
Number of Shares	389,731	389,731
Weighted-Average Exercise Price	$ 0.01
July 2020 Private Placement first closing warrants
Class of Warrant or Right
Number of Shares	2,764,227	2,764,227
Weighted-Average Exercise Price	$ 2.58