Results of Operations (Details) (USD $)
In Thousands, unless otherwise specified
3 Months Ended 9 Months Ended
Sep. 30, 2012
Sep. 30, 2011
Sep. 30, 2012
Sep. 30, 2011
Numerator        
Net income ( loss) $ 4,855 $ (4,991) $ (5,462) $ (9,176)
Denominator        
Weighted average shares outstanding 18,568 13,522 16,523 13,492
Less: Weighted average shares subject to repurchase          (1)
Weighted average common shares outstanding - basic 18,568 13,522 16,523 13,491
Effect of dilutive equity incentive plans 664         
Weighted average common shares outstanding - diluted 19,232 13,522 16,523 13,491