Stock-Based Compensation (Details 1) (Details) (USD $)
In Thousands, except Share data, unless otherwise specified
 9 Months Ended
Sep. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]  
Options Outstanding, Shares, Beginning of Period 15,398,221
Options Outstanding, Shares, Granted 1,341,550
Options Outstanding, Shares, Options exercised (1,135,956)
Options Outstanding, Shares, Canceled (7,578)
Options Outstanding, Shares, Forfeited (261,897)
Options Outstanding, Shares, End of Period 15,334,340
Options Outstanding, Shares, Vested and Expected to Vest 14,341,565
Options Outstanding, Shares, Exercisable 7,938,908
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]  
Options Outstanding, Weighted Average Exercise Price, Beginning of Period, USD per share $ 4.92
Options Outstanding, Weighted Average Exercise Price, Options granted, USD per share $ 23.18
Options Outstanding, Weighted Average Exercise Price, Options exercised, USD per share $ 1.47
Options Outstanding, Weighted Average Exercise Price, Options canceled, USD per share $ 6.81
Options Outstanding, Weighted Average Exercise Price, Options forfeited, USD per share $ 8.51
Options Outstanding, Weighted Average Exercise Price, End of Period, USD per share $ 6.71
Options Outstanding, Weighted Average Exercise Price Per Share, Vested and Expected to Vest, USD per share $ 6.43
Options Outstanding, Weighted Average Exercise Price Per Share, Exercisable, USD per share $ 2.96
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]  
Options Outstanding, Aggregate Intrinsic Value $ 989,592
Options Outstanding, Aggregate Intrinsic Value, Vested and Expected to Vest 929,520
Options Outstanding, Aggregate Intrinsic Value, Exercisable $ 542,102