Net loss per common stock - Schedule of Securities Excluded From Computation of Earnings Per Share (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from computation of earnings per share (in shares)	7,057,310	5,912,538
Outstanding stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from computation of earnings per share (in shares)	6,848,289	5,840,538
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from computation of earnings per share (in shares)	186,500	72,000
Shares issuable under 2020 ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from computation of earnings per share (in shares)	22,521	0