Statements of Convertible Preferred Stock and Stockholders' Equity (Unaudited) - USD ($)	Convertible Preferred Stock Series A (Mezzanine) [Member]	Convertible Preferred Stock Series B [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Treasury Stock [Member]	Accumulated Deficit [Member]	Total
Beginning Balance at Dec. 31, 2018	$ 5,960,475		$ 59,058	$ 478,179,574	$ (205,999)	$ (476,721,490)	$ 1,311,143
Beginning Balance, Shares at Dec. 31, 2018	23,900		59,058,297
Issuance of common stock and warrants			$ 33	16,390			16,423
Issuance of common stock and warrants, Shares			33,087
Share-based compensation			$ 167	147,787			147,954
Share-based compensation, shares			166,962
Components of net loss						(2,122,820)	(2,122,820)
Employee stock purchase plan			$ 15	15,049			15,064
Employee stock purchase plan, Shares			14,625
Preferred stock conversion	$ (5,121)		$ 35	5,086			5,121
Preferred stock conversion, shares	(20)		35,266
Ending Balance at Mar. 31, 2019	$ 5,955,354		$ 59,308	478,363,886	(205,999)	(478,844,310)	(627,115)
Ending Balance, Shares at Mar. 31, 2019	23,880		59,308,237
Beginning Balance at Dec. 31, 2019	$ 5,758,190	$ 5,610	$ 68,530	504,211,040	(205,999)	(481,312,774)	22,766,407
Beginning Balance, Shares at Dec. 31, 2019	23,110	5,610,121	68,529,623
Issuance of common stock and warrants			$ 41	(23,891)			(23,850)
Issuance of common stock and warrants, Shares			40,816
Share-based compensation			$ 109	722,203			722,312
Share-based compensation, shares			109,489
Components of net loss						(1,971,531)	(1,971,531)
Employee stock purchase plan			$ 7	32,216			32,223
Employee stock purchase plan, Shares			6,406
Preferred stock conversion	$ (49,163)		$ 354	48,809			49,163
Preferred stock conversion, shares	(192)		354,447
Ending Balance at Mar. 31, 2020	$ 5,709,027	$ 5,610	$ 69,041	$ 504,990,377	$ (205,999)	$ (483,284,305)	$ 21,574,724
Ending Balance, Shares at Mar. 31, 2020	22,918	5,610,121	69,040,781