Preferred and Common Stock Warrants - Summary of Outstanding Warrants to Purchase Shares of Common Stock (Details) - $ / shares	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Class of Warrant or Right [Line Items]
Class of warrant or right, outstanding (in shares)	13,354,403	13,656,871	5,146,400
Issuance On October 25, 2016
Class of Warrant or Right [Line Items]
Class of warrant or right, outstanding (in shares)	5,155
Exercise Price (in dollars per share)	$ 19.78
Issuance On December 28, 2017
Class of Warrant or Right [Line Items]
Class of warrant or right, outstanding (in shares)	115,916
Exercise Price (in dollars per share)	$ 19.78
Issuance On September 12, 2018
Class of Warrant or Right [Line Items]
Class of warrant or right, outstanding (in shares)	25,275
Exercise Price (in dollars per share)	$ 19.78
Issuance On September 12, 2018
Class of Warrant or Right [Line Items]
Class of warrant or right, outstanding (in shares)	20,220
Exercise Price (in dollars per share)	$ 19.78
Issuance On October 19, 2018
Class of Warrant or Right [Line Items]
Class of warrant or right, outstanding (in shares)	20,016
Exercise Price (in dollars per share)	$ 19.78
Issuance On March 13, 2019
Class of Warrant or Right [Line Items]
Class of warrant or right, outstanding (in shares)	5,000
Exercise Price (in dollars per share)	$ 19.78
Issuance On April 16, 2019
Class of Warrant or Right [Line Items]
Class of warrant or right, outstanding (in shares)	3,866,154
Exercise Price (in dollars per share)	$ 13.20
Issuance On April 16, 2019
Class of Warrant or Right [Line Items]
Class of warrant or right, outstanding (in shares)	2,130,000
Exercise Price (in dollars per share)	$ 11.00
Issuance on November 29, 2019
Class of Warrant or Right [Line Items]
Class of warrant or right, outstanding (in shares)	5,416,667
Exercise Price (in dollars per share)	$ 15.00
Issuance on November 29, 2019
Class of Warrant or Right [Line Items]
Class of warrant or right, outstanding (in shares)	1,750,000
Exercise Price (in dollars per share)	$ 12.00