Summary of Significant Accounting Policies - Net Loss per Share (Details) - shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Anti-dilutive securities
Total shares excluded from diluted net loss per share applicable to common stockholders	3,753,025	3,162,111
Weighted Average Number of Shares Outstanding, Basic and Diluted	30,335,164	23,393,448
Employee Stock options
Anti-dilutive securities
Total shares excluded from diluted net loss per share applicable to common stockholders	3,753,025	3,158,558
Restricted stock
Anti-dilutive securities
Total shares excluded from diluted net loss per share applicable to common stockholders		3,553