STATEMENTS OF STOCKHOLDERS EQUITY (DEFICIT) - USD ($)
shares in Thousands, $ in Thousands
Common Stock [Member]
Additional Paid-in Capital [Member]
Employees and Directors [Member]
Additional Paid-in Capital [Member]
Non-employee [Member]
Additional Paid-in Capital [Member]
Accumulated Deficit [Member]
Employees and Directors [Member]
Non-employee [Member]
Total
Beginning Balance (in shares) at Dec. 31, 2012 99,814              
Beginning Balance at Dec. 31, 2012 $ 100     $ 308,283 $ (246,606)     $ 61,777
Issuance of common stock upon exercise of options (in shares) 35             35
Issuance of common stock upon exercise of options       55       $ 55
Stock-based compensation   $ 5,069 $ 127     $ 5,069 $ 127  
Net loss and comprehensive loss         (46,011)     (46,011)
Ending Balance (in shares) at Dec. 31, 2013 99,849              
Ending Balance at Dec. 31, 2013 $ 100     313,534 (292,617)     $ 21,017
Issuance of common stock upon exercise of options (in shares) 1,381             1,381
Issuance of common stock upon exercise of options $ 1     1,776       $ 1,777
Issuance of common stock upon exercise of warrants (in shares) 165              
Stock-based compensation   4,731 470     4,731 470  
Net loss and comprehensive loss         (31,383)     (31,383)
Ending Balance (in shares) at Dec. 31, 2014 101,395              
Ending Balance at Dec. 31, 2014 $ 101     320,511 (324,000)     $ (3,388)
Issuance of common stock upon exercise of options (in shares) 2,041             2,041
Issuance of common stock upon exercise of options $ 3     5,190       $ 5,193
Issuance of common stock upon exercise of warrants (in shares) 6,206              
Issuance of common stock upon exercise of warrants $ 6     17,082       17,088
Stock-based compensation   $ 5,926 $ 87     $ 5,926 $ 87  
Net loss and comprehensive loss         (6,408)     (6,408)
Ending Balance (in shares) at Dec. 31, 2015 109,642              
Ending Balance at Dec. 31, 2015 $ 110     $ 348,796 $ (330,408)     $ 18,498