Summary of Significant Accounting Policies - Basic and Diluted Loss Per Common Share (Details) - shares	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
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)	1,137,507	976,711
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)	104,127	157,262
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