Stockholders' Equity (Deficit) - Shares Reserved for Future Issuance (Details) - shares	Dec. 31, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	6,660,892	6,237,832
Exercise of options under stock plan
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	4,237,828	4,310,790
Issuance of options and restricted stock units under stock plan
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	1,790,687	1,554,690
Issuance of common stock under employee stock purchase plan
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	632,377	372,352