Stockholders' Equity - Common stock (Details)	12 Months Ended
	Dec. 31, 2020 vote shares	Dec. 31, 2019 shares
Class of Stock [Line Items]
Number of shares reserved for future issuance (in shares)	6,869,189	7,782,582
Common Stock
Class of Stock [Line Items]
Number of votes per common share | vote	1
Warrants and share-based payment awards
Class of Stock [Line Items]
Number of shares reserved for future issuance (in shares)	6,869,189	7,782,582
Share-based payments | Stock options
Class of Stock [Line Items]
Number of shares reserved for future issuance (in shares)	6,112,948	4,720,772
Share-based payments | Restricted stock units
Class of Stock [Line Items]
Number of shares reserved for future issuance (in shares)	716,767	447,336
Warrants
Class of Stock [Line Items]
Number of shares reserved for future issuance (in shares)	39,474	39,474
Exchange warrants
Class of Stock [Line Items]
Number of shares reserved for future issuance (in shares)	0	2,575,000