Statements Of Shareholders' Equity (USD $)	Common Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Warrant [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Total
Shareholders' equity - beginning of year at Dec. 31, 2010	$ 527,520	$ (7,816)	$ 16,534,516	$ 226,780,738	$ (227,243,250)	$ 16,591,708
Shareholders' equity - beginning of year, shares at Dec. 31, 2010	52,752,036
Issuance of common stock upon exercise of options and warrants	6,875			498,867		330,938
Issuance of common stock upon exercise of options and warrants, shares	687,461
Issuance of common stock and warrants in private and public offerings	138,235			10,001,901		10,556,754
Issuance of common stock and warrants in private and public offerings, shares	13,823,477
Share-based compensation	3,108			1,434,066		1,437,174
Share-based compensation, shares	310,801
Change in unrealized (loss) gain on available for sale securities		(2,602)
Exercise of warrants			(174,804)
Expiration of warrants			(8,126,544)	8,126,544
Issuance of warrants in connection with pubilc offering			416,618
Net loss					(14,573,353)	(14,573,353)
Comprehensive loss						(14,575,955)
Shareholders' equity - end of year at Dec. 31, 2011	675,738	(10,418)	8,649,786	246,842,116	(241,816,603)	14,340,619
Shareholders' equity - end of year, shares at Dec. 31, 2011	67,573,775
Issuance of common stock upon exercise of options and warrants	22,581			2,042,922		1,381,694
Issuance of common stock upon exercise of options and warrants, shares	2,258,188
Issuance of common stock and warrants in private and public offerings	125,209			17,430,465		17,555,674
Issuance of common stock and warrants in private and public offerings, shares	12,520,811
Share-based compensation	5,508			3,547,906		3,553,414
Share-based compensation, shares	550,835
Change in unrealized (loss) gain on available for sale securities		10,398
Exercise of warrants			(683,809)
Expiration of warrants			(6,884,927)	6,884,927
Issuance of warrants in connection with pubilc offering			0
Net loss					(20,321,812)	(20,321,812)
Comprehensive loss						(20,311,414)
Shareholders' equity - end of year at Dec. 31, 2012	829,036	(20)	1,081,050	276,748,336	(262,138,415)	16,519,987
Shareholders' equity - end of year, shares at Dec. 31, 2012	82,903,609					82,903,609
Issuance of common stock upon exercise of options and warrants	11,975			1,553,355		1,147,380
Issuance of common stock upon exercise of options and warrants, shares	1,197,541
Issuance of common stock and warrants in private and public offerings	83,966			27,244,009		27,327,975
Issuance of common stock and warrants in private and public offerings, shares	8,396,573
Share-based compensation	7,108			6,924,330		6,931,438
Share-based compensation, shares	710,748
Change in unrealized (loss) gain on available for sale securities		(8,195)
Exercise of warrants			(417,950)
Expiration of warrants			0	0
Issuance of warrants in connection with pubilc offering			0
Net loss					(27,872,293)	(27,872,293)
Comprehensive loss						(27,880,488)
Shareholders' equity - end of year at Dec. 31, 2013	$ 932,085	$ (8,215)	$ 663,100	$ 312,470,030	$ (290,010,708)	$ 24,046,292
Shareholders' equity - end of year, shares at Dec. 31, 2013	93,208,471					93,208,471