Financial Information by Quarter (Unaudited) (Details) (USD $)
3 Months Ended 12 Months Ended
Dec. 31, 2013
Sep. 30, 2013
Jun. 30, 2013
Mar. 31, 2013
Dec. 31, 2012
Sep. 30, 2012
Jun. 30, 2012
Mar. 31, 2012
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Quarterly Financial Information [Abstract]                      
Research and development $ 934,000 $ 2,292,000 $ 965,000 $ 1,328,000 $ 2,514,000 $ 2,290,000 $ 2,701,000 $ 1,466,000 $ 5,519,300 $ 8,970,835 $ 12,725,792
Selling, general and administrative expense 3,782,000 3,266,000 3,166,000 3,031,000 2,583,000 3,139,000 3,475,000 2,214,000 13,244,819 11,410,131 23,931,713
Research and development expense 2,819,000 4,261,000 3,131,000 3,645,000 4,396,000 4,170,000 5,183,000 4,465,000 13,856,500 18,213,036 18,367,348
Patent preparation fees 333,000 329,000 301,000 458,000 794,000 377,000 376,000 336,000 1,421,218 1,883,405 1,808,168
Restructuring charges 513,000 0 0 0         512,944 0 0
Operating loss (6,513,000) (5,564,000) (5,633,000) (5,807,000) (5,259,000) (5,396,000) (6,332,000) (5,549,000) (23,516,181) (22,535,737) (31,381,437)
Net income (loss) $ (4,338,000) $ (4,902,000) $ (3,061,000) $ (4,876,000) $ (2,618,000) $ (3,059,000) $ (3,767,000) $ (4,616,000) $ (17,177,333) $ (14,059,539) $ 29,099,579
Earning (loss) per share: basic and diluted $ (0.08) $ (0.09) $ (0.06) $ (0.09) $ (0.04) $ (0.06) $ (0.07) $ (0.09)