Summary of Significant Accounting Policies - Antidilutive Securities (Details) - shares	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Net Loss Per Share
Antidilutive securities excluded from the calculation of basic and diluted loss per share (in shares)	11,233,583	12,696,096
Stock Option
Net Loss Per Share
Antidilutive securities excluded from the calculation of basic and diluted loss per share (in shares)	4,687,566	8,117,024
Warrants
Net Loss Per Share
Antidilutive securities excluded from the calculation of basic and diluted loss per share (in shares)	5,505,901	4,515,947
Restricted Stock Units (RSUs)
Net Loss Per Share
Antidilutive securities excluded from the calculation of basic and diluted loss per share (in shares)	976,991	0
Series A Convertible Preferred Stock
Net Loss Per Share
Antidilutive securities excluded from the calculation of basic and diluted loss per share (in shares)	63,125	63,125