Summary of Significant Accounting Policies (EPS) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net loss per share
Net loss									$ (40,166)	$ (41,230)	$ (5,811)
Weighted average common shares outstanding, basic and diluted									18,233,177	15,770,972	2,545,371
Net loss per share attributable to common stockholders	$ (0.43)	$ (0.55)	$ (0.56)	$ (0.66)	$ (1.57)	$ (0.43)	$ (0.20)	$ (0.23)	$ (2.20)	$ (2.61)	$ (2.28)
Potentially dilutive securities
Potentially dilutive securities									2,105,006	2,015,616	1,661,254
Stock options
Potentially dilutive securities
Potentially dilutive securities									2,057,296	1,967,906	1,613,544
Warrants
Potentially dilutive securities
Potentially dilutive securities									47,710	47,710	47,710