Net Loss Per Share Attributable to Common Stockholders (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2015

Dec. 31, 2014

Net Loss Per Share Attributable to Common Stockholders

Schedule of outstanding potentially dilutive securities excluded from the calculation of diluted net loss per common share

	Nine Months Ended
	September 30,
	2015		2014
Shares of common stock issuable upon conversion of preferred stock		—		2,010,596
Shares of common stock subject to outstanding options and restricted stock units		905,302		832,407
Warrants to purchase common stock		605,872		257,663
Total shares of common stock equivalents		1,511,174		3,100,666

	December 31, 2013		December 31, 2014
Convertible preferred stock		—		2,010,596
Options		—		659,554
Warrants to purchase common stock		207,664		257,663
Restricted stock units		—		68,902
Total		207,664		2,927,813