CONDENSED STATEMENTS OF STOCKHOLDERS' DEFICIT - 6 months ended Jun. 30, 2016 - USD ($)	Total	Convertible Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]
Balance at Dec. 31, 2015	$ (2,461,400)	$ 0	$ 172,889	$ 126,354,036	$ (128,988,325)
Balance (in shares) at Dec. 31, 2015		0	172,887,221
Net loss	(3,604,936)	$ 0	$ 0	0	(3,604,936)
Horizon warrant	5,924	0	0	5,924	0
Employee stock purchase plan	7,131	$ 0	$ 143	6,988	0
Employee stock purchase plan (in shares)		0	142,619
Stock-based compensation expense	429,528	$ 0	$ 0	429,528	0
Balance at Jun. 30, 2016	$ (5,623,753)	$ 0	$ 173,032	$ 126,796,476	$ (132,593,261)
Balance (in shares) at Jun. 30, 2016		0	173,029,840