CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME/LOSS (USD $)
 12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Revenues      
Research and development $ 5,519,300 $ 8,970,835 $ 12,725,792
Operating expenses      
Selling, general and administrative 13,244,819 11,410,131 23,931,713
Research and development 13,856,500 18,213,036 18,367,348
Patent preparation fees 1,421,218 1,883,405 1,808,168
Restructuring charges 512,944 0 0
Total operating expenses 29,035,481 31,506,572 44,107,229
Operating loss (23,516,181) (22,535,737) (31,381,437)
Decrease (increase) in fair value of common stock warrants (73,756) 804,516 24,436,309
Non-cash interest expense (1,207,332) (172,993) 0
Other income, net 1,497 522 13,061
Loss before income taxes (24,795,772) (21,903,692) (6,932,067)
Benefit from (provision for) income taxes 7,618,439 7,844,153 36,031,646
Net income (loss) (17,177,333) (14,059,539) 29,099,579
Earning (loss) per share: basic $ (0.33) $ (0.27) $ 0.57
Earnings (loss) per share: diluted $ (0.33) $ (0.27) $ 0.09
Weighted average shares: basic 52,368,842 51,639,622 50,929,491
Weighted average shares outstanding: diluted 52,368,842 51,639,622 54,061,650
Comprehensive income (loss)      
Net income (loss) (17,177,333) (14,059,539) 29,099,579
Change in net unrealized gain (loss) on short-term investments 0 0 (4,067)
Comprehensive income (loss) $ (17,177,333) $ (14,059,539) $ 29,095,512