Condensed Statements of Redeemable Convertible Preferred Stock and Stockholders Equity (Deficit) - 9 months ended Sep. 30, 2015 - USD ($)	Total	Common Stock	Additional Paid-In-Capital (Distributions in Excess of Capital)	Treasury Stock	Accumulated Other Comprehensive Income	Accumulated Deficit	Series A Redeemable Convertible Preferred Stock	Series B Redeemable Convertible Preferred Stock	Series C-1 Redeemable Convertible Preferred Stock	Series C-2 Redeemable Convertible Preferred Stock	Series D Redeemable Convertible Preferred Stock	Series E Redeemable Convertible Preferred Stock
Balance at Dec. 31, 2014	$ (69,669,926)	$ 333	$ (1,426,556)	$ (75,000)		$ (68,168,703)	$ 1,402,687	$ 2,099,310	$ 4,567,525	$ 2,223,506	$ 37,174,666	$ 8,454,899
Balance, Redeemable convertible preferred stock shares at Dec. 31, 2014							1,292,084	6,789,712	13,242,612	9,948,331	139,529,173	45,938,041
Exercise of Series D and Series E warrants											$ 93,550	$ 11,312
Exercise of Series D and Series E warrants, shares											723,505	51,681
Exercise of stock options	34,048	$ 14	34,034
Exercise of stock options, shares		13,766
Share-based compensation expense	223,787		223,787
Accretion of redeemable convertible preferred stock issuance costs	(35,046)		(35,046)				$ 320	$ 839	$ 1,538	$ 2,113	$ 18,109	$ 12,127
Accretion of Series E warrant discount	(127,616)		(127,616)									127,616
Accretion of Series D and E redeemable convertible preferred stock dividend	(1,165,932)		(1,165,932)								876,955	288,977
Settlement of outstanding principal and accrued interest on convertible notes by issuance of common stock	4,544,384	$ 324	4,544,060
Settlement of outstanding principal and accrued interest on convertible notes by issuance of common stock, shares		324,591
Conversion of warrants from warrants for preferred stock to warrants for common stock	1,616,140		1,616,140
Conversion of preferred stock into common stock at initial public offering	57,356,049	$ 2,509	57,353,540				$ (1,403,007)	$ (2,100,149)	$ (4,569,063)	$ (2,225,619)	$ (38,163,280)	$ (8,894,931)
Conversion of preferred stock into common stock at initial public offering, shares		2,508,824					(1,292,084)	(6,789,712)	(13,242,612)	(9,948,331)	(140,252,678)	(45,989,722)
Issuance of common stock from initial public offering	45,354,186	$ 3,660	45,350,526
Issuance of common stock from initial public offering, shares		3,660,076
Net loss	(15,698,139)					(15,698,139)
Balance at Sep. 30, 2015	22,436,689	$ 6,840	$ 106,366,937	$ (75,000)	$ 4,754	$ (83,866,842)
Balance, shares at Dec. 31, 2014		332,607
Other comprehensive income	$ 4,754				$ 4,754
Balance, shares at Sep. 30, 2015		6,827,414