Consolidated Statements of Stockholders' Equity (USD $)
Total
Common Stock
Preferred Stock
Additional Paid-in Capital
Accumulated Other Comprehensive Income (Loss)
Accumulated Deficit
Beginning Balances at Dec. 31, 2010 $ 52,111,000 $ 116,000    $ 369,686,000 $ (746,000) $ (316,945,000)
Beginning Balances (in shares) at Dec. 31, 2010   115,611,000        
Issuance of common stock upon exercise of stock options and restricted stock awards 10,000       10,000      
Issuance of common stock upon exercise of stock options and restricted stock awards (In Shares)   308,000        
Issuance of common stock under Employee Stock Purchase Plan 132,000       132,000      
Issuance of common stock under Employee Stock Purchase Plan (in shares)   106,000        
Proceeds from issuances of common stock and warrants, net of issuance costs 91,298,000 39,000    91,259,000      
Proceeds from issuances of common stock and warrants, net of issuance costs (in shares)   38,601,000        
Stock compensation expense 5,189,000       5,189,000      
Total other comprehensive income (loss) (263,000)          (263,000)   
Net loss (48,597,000)             (48,597,000)
Ending Balances at Dec. 31, 2011 99,880,000 155,000    466,276,000 (1,009,000) (365,542,000)
Ending Balances (in shares) at Dec. 31, 2011   154,626,000        
Issuance of common stock upon exercise of stock options and restricted stock awards 1,955,000 1,000    1,954,000      
Issuance of common stock upon exercise of stock options and restricted stock awards (In Shares)   1,222,000        
Issuance of common stock under Employee Stock Purchase Plan 307,000       307,000      
Issuance of common stock under Employee Stock Purchase Plan (in shares)   141,000        
Proceeds from issuances of common stock and warrants, net of issuance costs 71,780,000 27,000    71,753,000      
Proceeds from issuances of common stock and warrants, net of issuance costs (in shares)   26,803,000        
Stock compensation expense 10,439,000       10,439,000      
Total other comprehensive income (loss) 414,000          414,000   
Net loss (69,949,000)             (69,949,000)
Ending Balances at Dec. 31, 2012 114,826,000 183,000    550,729,000 (595,000) (435,491,000)
Ending Balances (in shares) at Dec. 31, 2012   182,792,000        
Issuance of common stock upon exercise of stock options and restricted stock awards 112,000      112,000     
Issuance of common stock upon exercise of stock options and restricted stock awards (In Shares)   106,000        
Issuance of common stock under Employee Stock Purchase Plan 224,000      224,000     
Issuance of common stock under Employee Stock Purchase Plan (in shares)   129,000        
Restricted Stock Award Delivered (in shares)   115,000        
Issuance of common stock, net of issuance costs 80,999,000 80,000   80,919,000     
Issuance of common stock, net of issuance costs (in shares)   79,570,000        
Issuance of Series B convertible preferred stock, net of issuance costs 44,209,000      44,209,000     
Issuance of Series B convertible preferred stock, net of issuance costs (in shares)     43,000      
Beneficial conversion feature of Series B convertible preferred stock                  
Deemed dividend to holders of Series B convertible preferred stock                  
Warrants exercised                  
Warrants exercised (in shares)   84,000        
Stock compensation expense 12,340,000     12,340,000    
Total other comprehensive income (loss) 447,000       447,000  
Net loss (66,720,000)         (66,720,000)
Initial expenses related to ATM agreement (143,000)     (143,000)    
Ending Balances at Dec. 31, 2013 $ 186,294,000 $ 263,000   $ 688,390,000 $ (148,000) $ (502,211,000)
Ending Balances (in shares) at Dec. 31, 2013   262,796,000 43,000