Net Loss Per Common Share - Calculation of diluted net loss per share (Details) - shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Net Income (Loss) Per Common Share
Total potential dilutive shares (in shares)	49,670,635	13,054,817	4,923,895
Common shares under option
Net Income (Loss) Per Common Share
Total potential dilutive shares (in shares)	3,214,537	4,176,518	4,677,929
Unvested RSUs
Net Income (Loss) Per Common Share
Total potential dilutive shares (in shares)	698,704	401,234	245,966
Shares issuable related to the ESPP
Net Income (Loss) Per Common Share
Total potential dilutive shares (in shares)	23,448	16,828	0
Unvested PBRSUs
Net Income (Loss) Per Common Share
Total potential dilutive shares (in shares)	639,950	0	0
Common shares under PBSOs
Net Income (Loss) Per Common Share
Total potential dilutive shares (in shares)	122,700	0	0
Shares issuable upon conversion of convertible notes
Net Income (Loss) Per Common Share
Total potential dilutive shares (in shares)	8,007,010	8,460,237	0
Warrants for common stock
Net Income (Loss) Per Common Share
Total potential dilutive shares (in shares)	36,964,286	0	0