Summary of Significant Accounting Policies - Basic and Diluted Loss Per Common Share (Details) - shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Stock options
Anti-dilutive securities
Outstanding securities not included in the computation of diluted net loss per common share as their inclusion would be anti-dilutive (in shares)	1,367,077	1,122,585
Unvested Restricted Common Stock
Anti-dilutive securities
Outstanding securities not included in the computation of diluted net loss per common share as their inclusion would be anti-dilutive (in shares)	52,063	104,127
Preferred Stock
Anti-dilutive securities
Outstanding securities not included in the computation of diluted net loss per common share as their inclusion would be anti-dilutive (in shares)	1,969,797	1,969,797