Summary of Significant Accounting Policies - Net Loss per Share (Details) - shares	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Anti-dilutive securities
Total shares excluded from diluted net loss per share applicable to common stockholders	8,647,368	3,858,146
Stock options
Anti-dilutive securities
Total shares excluded from diluted net loss per share applicable to common stockholders	4,741,000	3,858,146
Unvested Restricted Stock
Anti-dilutive securities
Total shares excluded from diluted net loss per share applicable to common stockholders	1,122,024
Warrants
Anti-dilutive securities
Total shares excluded from diluted net loss per share applicable to common stockholders	2,118,344
Convertible Preferred Stock
Anti-dilutive securities
Total shares excluded from diluted net loss per share applicable to common stockholders	666,000