v2.4.0.8
Employee Stock and Benefit Plans (Stock Option Activity) (Details) (USD $)
In Thousands, except Share data, unless otherwise specified
 12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Outstanding Shares        
Beginning balance (in shares) 6,513,508 6,312,041 5,600,875  
Granted (in shares) 2,001,400 1,478,781 1,816,850  
Exercised (in shares) (952,871) (724,316) (432,687)  
Canceled (in shares) (522,944) (552,998) (672,997)  
Ending balance (in shares) 7,039,093 6,513,508 6,312,041 5,600,875
Vested and Expected to vest (in shares) 6,472,113      
Exercisable (in shares) 5,331,893      
Weighted Average Exercise Price        
Weighted average exercise price, beginning balance (in dollars per share) $ 4.39 $ 3.36 $ 2.86  
Weighted average exercise price, granted (in dollars per share) $ 15.78 $ 8.94 $ 5.06  
Weighted average exercise price, exercised (in dollars per share) $ 4.32 $ 2.86 $ 3.09  
Weighted average exercise price, canceled (in dollars per share) $ 10.71 $ 6.79 $ 3.89  
Weighted average exercise price, ending balance (in dollars per share) $ 7.17 $ 4.39 $ 3.36 $ 2.86
Vested and Expected to vest, weighted average exercise price (in dollars per share) $ 6.49      
Exercisable, Weighted average exercise price (in dollars per share) $ 4.32      
Weighted Average Remaining Contractual Life (Years)        
Weighted average remaining contractual life 6 years 6 months 6 years 7 months 6 days 6 years 10 months 24 days 6 years 4 months 24 days
Vested and Expected to vest, weighted average remaining contractual life 6 years 3 months 18 days      
Exercisable, weighted average remaining contractual life 5 years 9 months 18 days      
Aggregate Intrinsic Value        
Aggregate intrinsic value $ 112,312 $ 67,711 $ 16,012 $ 6,964
Vested and Expected to vest, aggregate intrinsic value 107,622      
Exercisable, aggregate intrinsic value $ 85,073