Net Income (Loss) Per Share - Antidilutive Shares (Details)
In Thousands, unless otherwise specified
 3 Months Ended 6 Months Ended 9 Months Ended
Sep. 30, 2012
Jun. 30, 2011
Jun. 30, 2011
Sep. 30, 2012
Stock options [Member]
        
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Antidilutive common stock equivalent shares excluded from calculation of diluted net income (loss) per share (in shares) 6,400 11,501 6,831 10,186
Unvested RSUs [Member]
        
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Antidilutive common stock equivalent shares excluded from calculation of diluted net income (loss) per share (in shares) 1,198 2,234 1,812 1,559
Common stock warrants [Member]
        
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Antidilutive common stock equivalent shares excluded from calculation of diluted net income (loss) per share (in shares) 375 375 375 375
ESPP shares [Member]
        
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Antidilutive common stock equivalent shares excluded from calculation of diluted net income (loss) per share (in shares) 827 1,601 1,601 827