Statements of Changes in Stockholders' Equity - USD ($)	Total	Series B – F Preferred Stock	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Series D Preferred Stock	Series D Preferred Stock Series B – F Preferred Stock	Series D Preferred Stock Additional Paid-In Capital	Series E Preferred Stock	Series E Preferred Stock Series B – F Preferred Stock	Series E Preferred Stock Additional Paid-In Capital	Series F Preferred Stock	Series F Preferred Stock Series B – F Preferred Stock	Series F Preferred Stock Additional Paid-In Capital
Beginning Balance at Dec. 31, 2015	$ 12,562,708	$ 21	$ 51	$ 176,128,286	$ (163,565,650)
Beginning Balance (in shares) at Dec. 31, 2015		20,946	505,917
Stock-based compensation expense	225,408			225,408
Issuance of Series D preferred stock and warrants and redemption of Series C preferred stock under purchase agreement						$ 6,738,500	$ 8	$ 6,738,492
Issuance of Series D preferred stock and warrants and redemption of Series C preferred stock under purchase agreement (in shares)							7,500
Issuance of common stock upon conversion of preferred stock	0	$ (11)	$ 30	(19)
Issuance of common stock upon conversion of preferred stock (in shares)		(10,743.35)	(304,311)
Issuance of common stock under employees stock purchase plan	28,538		$ 1	28,537
Issuance of common stock under employee stock purchase plan (in shares)			4,375
Common stock issued to settle incentive compensation obligations	318,761		$ 2	318,759
Common stock issued to settle incentive compensation obligations (in shares)			22,260
Net loss	(14,913,151)				(14,913,151)
Ending Balance at Dec. 31, 2016	4,960,764	$ 18	$ 84	183,439,463	(178,478,801)
Ending Balance (in shares) at Dec. 31, 2016		17,702.65	836,863
Stock-based compensation expense	209,691			209,691
Issuance of common stock upon conversion of preferred stock	0	$ (6)	$ 184	(178)
Issuance of common stock upon conversion of preferred stock (in shares)		(5,843.67)	(1,833,240)
Issuance of common stock under employees stock purchase plan	20,768		$ 1	20,767
Issuance of common stock under employee stock purchase plan (in shares)			11,583
Issuance of preferred stock and warrants under purchase agreement									$ 6,057,389	$ 7	$ 6,057,382	$ 6,628,030	$ 11	$ 6,628,019
Issuance of preferred stock and warrants under purchase agreement (in shares)										7,000			10,621
Issuance of common stock in exchange for warrants	0		$ 2	(2)
Issuance of common stock in exchange for warrants (in shares)			24,380
Net loss	(12,859,253)				(12,859,253)
Ending Balance at Dec. 31, 2017	$ 5,017,389	$ 30	$ 271	$ 196,355,142	$ (191,338,054)
Ending Balance (in shares) at Dec. 31, 2017		29,479.98	2,706,066