Summary of Significant Accounting Policies - Potentially dilutive securities (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Potentially dilutive securities
Potentially dilutive securities excluded from computation of diluted weighted average shares	1,586,946	1,510,253	4,042,945
Stock Options
Potentially dilutive securities
Potentially dilutive securities excluded from computation of diluted weighted average shares	1,498,390	1,421,697	490,134
Series A
Potentially dilutive securities
Potentially dilutive securities excluded from computation of diluted weighted average shares			911,336
Series B
Potentially dilutive securities
Potentially dilutive securities excluded from computation of diluted weighted average shares			2,552,919
Series B Redeemable Convertible Preferred Stock Warrants
Potentially dilutive securities
Potentially dilutive securities excluded from computation of diluted weighted average shares			88,556
Common Stock Warrants
Potentially dilutive securities
Potentially dilutive securities excluded from computation of diluted weighted average shares	88,556	88,556