Consolidated Statements of Stockholders' Equity (USD $)
In Thousands
Total
Common Stock [Member]
Additional Paid-In Capital [Member]
Accumulated Other Comprehensive (Loss) Income [Member]
Accumulated Deficit [Member]
Beginning Balance at Dec. 31, 2010 $ 65,503 $ 450 $ 361,520 $ 105 $ (296,572)
Net loss (56,948)       (56,948)
Other comprehensive loss (65)     (65)  
Exercise of stock options, 184, 348, 563 shares, net for the year 2011, 2012 and 2013 respectively 278 2 276    
Employee stock purchase plan sales, 94, 110, 89 shares for the year 2011, 2012 and 2013 respectively 300 1 299    
Issuance of common stock, 437, 4774, 7547 shares, net for the year 2011, 2012 and 2013 respectively 1,027 4 1,023    
Purchases of treasury stock, 12 shares (61)   (61)    
Stock-based compensation expense 4,772   4,772    
Ending Balance at Dec. 31, 2011 14,806 457 367,829 40 (353,520)
Net loss (39,081)       (39,081)
Other comprehensive loss (13)     (13)  
Exercise of stock options, 184, 348, 563 shares, net for the year 2011, 2012 and 2013 respectively 539 3 536    
Employee stock purchase plan sales, 94, 110, 89 shares for the year 2011, 2012 and 2013 respectively 321 1 320    
Issuance of common stock, 437, 4774, 7547 shares, net for the year 2011, 2012 and 2013 respectively 18,807 48 18,759    
Stock-based compensation expense 4,167   4,167    
Ending Balance at Dec. 31, 2012 (454) 509 391,611 27 (392,601)
Net loss (30,108)       (30,108)
Other comprehensive loss (23)     (23)  
Exercise of stock options, 184, 348, 563 shares, net for the year 2011, 2012 and 2013 respectively 1,333 6 1,327    
Employee stock purchase plan sales, 94, 110, 89 shares for the year 2011, 2012 and 2013 respectively 124 1 123    
Issuance of common stock, 437, 4774, 7547 shares, net for the year 2011, 2012 and 2013 respectively 23,634 75 23,559    
Stock-based compensation expense 4,368   4,368    
Ending Balance at Dec. 31, 2013 $ (1,126) $ 591 $ 420,988 $ 4 $ (422,709)