Net Loss Per Share - Antidilutive Securities (Details) - shares
3 Months Ended
Mar. 31, 2021
Mar. 31, 2020
Diluted net loss per share attributable to common stockholders    
Antidilutive securities excluded from computation of of diluted weighted average shares outstanding 18,141,571 17,249,162
Unvested restricted common stock    
Diluted net loss per share attributable to common stockholders    
Antidilutive securities excluded from computation of of diluted weighted average shares outstanding 724,854 299,700
Stock options to purchase common stock    
Diluted net loss per share attributable to common stockholders    
Antidilutive securities excluded from computation of of diluted weighted average shares outstanding 17,416,717 16,949,462