Financial Information by Quarter (Unaudited) Restatement (Details) - Condensed Consolidated Statements of Operations (USD $)	3 Months Ended									6 Months Ended		9 Months Ended		12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Jun. 30, 2012	Jun. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Research and Development Revenue	$ 1,465,752	$ 2,514,000	$ 2,289,820	$ 2,701,164	$ 1,466,000	$ 4,960,000	$ 3,577,948	$ 2,491,056	$ 1,696,721	$ 4,166,916	$ 4,187,777	$ 6,456,736	$ 7,765,725	$ 8,970,835	$ 12,725,792	$ 19,215,837
Total operating expenses	7,014,713		7,685,619	9,033,527			9,621,092	13,598,975	8,158,161	16,048,240	21,757,135	23,733,861	31,378,228	31,506,572	44,107,229	31,938,225
Operating loss	(5,548,961)	(5,259,000)	(5,395,799)	(6,332,363)	(5,549,000)	(7,769,000)	(6,043,144)	(11,107,919)	(6,461,440)	(11,881,324)	(17,569,358)	(17,277,125)	(23,612,503)	(22,535,737)	(31,381,437)	(12,722,388)
Change In Fair Value Of Common Stock Warrants	(999,529)		(133,375)	904,731			12,841,849	5,543,721	4,952,670	(94,798)	10,496,391	(228,173)	23,338,240	804,516	24,436,309	(38,110,030)
Interest Expense and Other Income	162		94	74			329	2,006	(2,793)	236	12,100	330	12,429
Benefit from (provision for) income taxes	1,932,719		2,470,346	1,660,720			1,527,275	32,907,988	1,511,563	3,593,439	32,895,101	6,063,785	34,422,376	7,844,153	36,031,646	(175,175)
Net income (loss)	(4,615,609)	(2,618,000)	(3,058,734)	(3,766,838)	(4,616,000)	(5,061,000)	8,326,309	27,345,796	(1,512,000)	(8,382,447)	25,834,234	(11,441,183)	34,160,542	(14,059,539)	29,099,579	(50,348,301)
Earnings Per Share, Basic and Diluted	$ (0.09)		$ (0.06)	$ (0.07)					$ (0.03)	$ (0.16)		$ (0.22)
Weighted Average Number of Shares Outstanding, Basic and Diluted	51,637,770		51,639,811	51,638,352					49,959,345	51,638,061		51,638,648
Earning (loss) per share: basic		$ (0.04)	$ (0.06)	$ (0.07)	$ (0.09)	$ (0.11)	$ 0.16	$ 0.54	$ (0.03)		$ 0.51		$ 0.67	$ (0.27)	$ 0.57	$ (1.12)
Earnings (loss) per share: diluted		$ (0.04)	$ (0.06)	$ (0.07)	$ (0.09)	$ (0.11)	$ 0.11	$ 0.40	$ (0.03)		$ 0.28		$ 0.20	$ (0.27)	$ 0.09	$ (1.12)
Weighted average shares: basic							50,806,284	50,879,599			50,422,014		50,739,475	51,639,622	50,929,491	45,151,774
Weighted Average Number of Shares Outstanding, Diluted							51,987,253	54,671,403			54,507,838		54,234,977	51,639,622	54,061,650	45,151,774
Scenario, Previously Reported [Member]
Research and Development Revenue	1,465,752		2,289,820	2,701,164		4,960,000	3,577,948	2,491,056	1,696,721	4,166,916	4,187,777	6,456,736	7,765,725	8,970,835	12,725,792	19,215,837
Total operating expenses	7,014,713		7,685,619	9,033,527			9,621,092	13,598,975	8,158,161	16,048,240	21,757,135	23,733,861	31,378,228	31,506,572	44,107,229	31,938,225
Operating loss	(5,548,961)		(5,395,799)	(6,332,363)		(7,769,000)	(6,043,144)	(11,107,919)	(6,461,440)	(11,881,324)	(17,569,358)	(17,277,125)	(23,612,503)	(22,535,737)	(31,381,437)	(12,722,388)
Change In Fair Value Of Common Stock Warrants	(436,813)		(15,032)	325,012			4,726,054	2,039,851	1,762,958	(111,801)	3,802,809	(126,833)	8,528,863	335,902	8,930,906	(15,957,068)
Interest Expense and Other Income	162		94	74			329	2,006	(2,793)	236	12,100	330	12,429
Benefit from (provision for) income taxes	1,932,719		2,470,346	1,660,720			1,527,275	32,907,988	4,701,275	3,593,439	32,895,101	6,063,785	34,422,376	7,844,153	36,031,646	(175,175)
Net income (loss)	(4,052,893)		(2,940,391)	(4,346,557)		(5,757,000)	210,514	23,841,926		(8,399,450)	19,140,652	(11,339,843)	19,351,165	(14,528,153)	13,594,176	(28,195,339)
Earnings Per Share, Basic and Diluted	$ (0.08)		$ (0.06)	$ (0.08)					$ (0.09)	$ (0.16)		$ (0.22)
Weighted Average Number of Shares Outstanding, Basic and Diluted	51,637,770		51,639,811	51,638,352					49,959,345	51,638,061		51,638,648
Earning (loss) per share: basic						$ (0.11)	$ 0.00	$ 0.47			$ 0.38		$ 0.38	$ (0.28)	$ 0.27	$ (0.62)
Earnings (loss) per share: diluted						$ (0.11)	$ 0.00	$ 0.40			$ 0.28		$ 0.20	$ (0.28)	$ 0.09	$ (0.62)
Weighted average shares: basic							50,806,284	50,879,599			50,422,014		50,739,475	51,639,622	50,929,491	45,151,774
Weighted Average Number of Shares Outstanding, Diluted							51,987,253	54,671,403			54,507,838		54,234,977	51,639,622	54,061,650	45,151,774
Revised Adjustment [Member]
Total operating expenses														0
Operating loss														0
Change In Fair Value Of Common Stock Warrants	(562,716)		(118,343)	579,719						17,003		(101,340)		468,614
Net income (loss)	(562,716)		(118,343)	579,719						17,003		(101,340)		468,614
Earnings Per Share, Basic and Diluted	$ (0.01)		$ 0.00	$ 0.01						$ 0.00		$ 0.00
Earning (loss) per share: basic														$ 0.01
Earnings (loss) per share: diluted														$ 0.01
Weighted average shares: basic														0
Weighted Average Number of Shares Outstanding, Diluted														0
Restatement Adjustment [Member]
Total operating expenses															0	0
Operating loss															0	0
Change In Fair Value Of Common Stock Warrants							8,115,795	3,503,870	3,189,712		6,693,582		14,809,377		15,505,403	(22,152,962)
Benefit from (provision for) income taxes									(3,189,712)
Net income (loss)							$ 8,115,795	$ 3,503,870			$ 6,693,582		$ 14,809,377		$ 15,505,403	$ (22,152,962)
Earnings Per Share, Basic and Diluted									$ 0.06
Earning (loss) per share: basic							$ 0.16	$ 0.07			$ 0.13		$ 0.29		$ 0.30	$ (0.50)
Earnings (loss) per share: diluted							$ 0.11	$ 0.00			$ 0.00		$ 0.00		$ 0.00	$ (0.50)
Weighted Average Number of Shares Outstanding, Diluted															0	0