Stock Plans (Details 4) (USD $)
In Thousands, except Share data, unless otherwise specified
6 Months Ended
Jun. 30, 2012
Supplemental disclosure of stock options  
Options exercisable, Shares 947,351
Options exercisable, Weighted- Average Exercise Price $ 2.18
Options exercisable, Weighted- Average Remaining Contractual Life (Years) 6 years 7 months 2 days
Options exercisable, Aggregate Intrinsic Value $ 25,235
Options outstanding, Shares 2,600,605
Options outstanding, Weighted- Average Exercise Price $ 9.33
Options outstanding, Weighted- Average Remaining Contractual Life (Years) 7 years 11 months 19 days
Options outstanding, Aggregate Exercise Price Intrinsic Value $ 52,410