Consolidated Statements of Change in Stockholders' Equity - USD ($)	Common Stock Warrants (Member) Common Stock [Member]	Common Stock Warrants (Member) Additional Paid-in Capital [Member]	Common Stock Warrants (Member)	Preferred Stock [Member] Prefered Stock [Member]	Preferred Stock [Member]	Common Stock [Member] Direct and ATM [Member]	Common Stock [Member] Prefered Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member] Direct and ATM [Member]	Additional Paid-in Capital [Member] Series A Redeemable Convertible Preferred Stock [Member]	Additional Paid-in Capital [Member] Hercules Warrant [Member]	Additional Paid-in Capital [Member] Prefered Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings [Member]	Direct and ATM [Member]	Series A Redeemable Convertible Preferred Stock [Member]	Hercules Warrant [Member]	Total
Balance at January 1 at Dec. 31, 2012								$ 84,373					$ 170,957,891	$ (2,690,511)	$ (126,607)	$ (156,263,288)				$ 11,961,858
Balance at January 1 (in Shares) at Dec. 31, 2012								8,289,507						147,760
Balance at December 31 at Dec. 31, 2013								$ 137,380					203,139,142	$ (2,421,364)	(44,166)	(169,287,157)				$ 31,523,835
Balance at December 31 (in Shares) at Dec. 31, 2013								13,604,975						132,995						863,462
Net loss																(8,251,358)				$ (8,251,358)
Stock offering					$ 150	$ 25,880			$ 15,598,670				18,217,702				$ 15,624,550			18,217,852
Stock offering (in Shares)					15,001	2,588,032
Classification of warrants to/from common stock warrant liability, net													(3,809,730)							(3,809,730)
Non-cash dividend on beneficial conversion feature associated with the preferred stock offering																(4,601,410)				$ (4,601,410)
Conversion of stock	$ 180	$ 261,764	$ 261,944	$ (150)			$ 26,828					$ (26,678)
Conversion of stock (in Shares)	18,021			(15,001)			2,682,759													15,833
Valuation of common stock warrants										$ 521,763								$ 521,763
Unrealized gain on investments available for sale															82,441					$ 82,441
Stock-based compensation expense													1,235,437							1,235,437
Issuance of restricted stock and option exercise								$ 129					183,918							184,047
Issuance of restricted stock and option exercise (in Shares)								12,872
Issuance of common stock out of treasury														$ 269,147		(171,101)				98,046
Issuance of common stock out of treasury (in Shares)								14,765						(14,765)
Fractional share payment								$ (10)					(1,595)							(1,605)
Fractional share payment (in Shares)								(981)
Balance at December 31 at Dec. 31, 2014								$ 200,976					229,778,703	$ (2,064,609)	(16,032)	(195,073,702)				$ 32,825,336
Balance at December 31 (in Shares) at Dec. 31, 2014								19,984,203						113,400						1,751,773
Net loss																(25,494,273)				$ (25,494,273)
Stock offering						$ 36,036			13,752,775								13,788,811
Stock offering (in Shares)						3,603,604
Common stock issued in connection with the acquisition of EGEN, Inc. assets								$ 27,122					10,823,855							10,850,977
Common stock issued in connection with the acquisition of EGEN, Inc. assets (in Shares)								2,712,188
Valuation of common stock warrants											$ (521,763)								$ (521,763)
Unrealized gain on investments available for sale															28,134					28,134
Stock-based compensation expense													2,513,042							2,513,042
Issuance of restricted stock								$ 438					71,652							72,090
Issuance of restricted stock (in Shares)								43,841
Issuance of common stock out of treasury														$ 356,755		(292,272)				64,483
Issuance of common stock out of treasury (in Shares)								19,595						(19,595)
Balance at December 31 at Dec. 31, 2015								$ 233,952					239,668,235	$ (1,382,305)	(3,858)	(218,130,360)				$ 20,385,664
Balance at December 31 (in Shares) at Dec. 31, 2015								23,319,287						75,924						2,221,340
Net loss																(22,461,084)				$ (22,461,084)
Stock offering						$ 32,836			$ 7,703,607								$ 7,736,443
Stock offering (in Shares)						3,283,608
Expiration of reset provision of the common stock warrants issued in connection with the November 2013 Hercules Loan													336,254							336,254
Unrealized gain on investments available for sale															$ 12,174					12,174
Stock-based compensation expense													1,828,896							1,828,896
Issuance of restricted stock								$ 140					$ 20,775							20,915
Issuance of restricted stock (in Shares)								14,000
Issuance of common stock out of treasury														$ 682,304		$ (595,574)				$ 86,730
Issuance of common stock out of treasury (in Shares)								37,476						(37,476)