CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS EQUITY (DEFICIT) - USD ($)	Total	Series B Preferred Stock	Series C Preferred Stock	Common Stock—Voting	Common Stock—Voting Series C Preferred Stock	Additional Paid-in Capital	Additional Paid-in Capital Series B Preferred Stock	Additional Paid-in Capital Series C Preferred Stock	Accumulated Deficit
BALANCES at Dec. 31, 2012	$ (101,803,622)			$ 10,413		$ 24,017,444			$ (125,831,479)
Shares, Outstanding at Dec. 31, 2012				10,413,467
Issuance of 7,952 shares of common stock for cash	49,891			$ 8		49,883
Issuance of 7,952 shares of common stock for cash, shares				7,952
Share-based compensation expense	978,352					978,352
Preferred Stock dividend accretion		$ (4,215,230)	$ (4,380,274)				$ (4,215,230)	$ (4,380,274)
Net loss	(21,687,155)								(21,687,155)
BALANCES at Dec. 31, 2013	(131,058,038)			$ 10,421		16,450,175			(147,518,634)
Shares, Outstanding at Dec. 31, 2013				10,421,419
Share-based compensation expense	1,553,985					1,553,985
Issuance of common stock to consultant for services	9,991			$ 1		9,990
Issuance of common stock to consultant for services, shares				666
Preferred Stock dividend accretion		$ (4,271,550)	(7,014,643)				$ (4,271,550)	(7,014,643)
Additional loss upon conversion of Series C Preferred Stock into common stock			(82,654,683)					(82,654,683)
Shares issued upon consummation of Initial Public Offering (IPO)	164,405,679			$ 11,979		164,393,700
Shares issued upon consummation of Initial Public Offering (IPO), shares				11,979,167
Conversion of Preferred Series C into common stock upon consummation of IPO			$ 199,760,975		$ 11,067			$ 199,749,908
Conversion of Preferred Series C into common stock upon consummation of IPO, shares					11,067,090
Net loss	(37,339,017)								(37,339,017)
BALANCES at Dec. 31, 2014	103,392,699			$ 33,468		288,216,882			(184,857,651)
Shares, Outstanding at Dec. 31, 2014				33,468,342
Exercise of options to purchase common stock	291,749			$ 44		291,705
Exercise of options to purchase common stock, shares				44,432
Issuance of restricted stock units				$ 24		(24)
Issuance of restricted stock units, shares				24,166
Share-based compensation expense	3,976,423					3,976,423
Net loss	(3,710,812)								(3,710,812)
BALANCES at Dec. 31, 2015	$ 103,950,060			$ 33,537		$ 292,484,986			$ (188,568,463)
Shares, Outstanding at Dec. 31, 2015				33,536,940