Quarterly report pursuant to Section 13 or 15(d)

Share- based Compensation (Details Textual)

v2.4.0.6
Share- based Compensation (Details Textual) (USD $)
1 Months Ended
Aug. 31, 2012
May 31, 2012
Apr. 30, 2012
Feb. 29, 2012
Share-based Compensation (Textual) [Abstract]        
Granted options 322,556 240,124   696,150
Exercise price $ 24.62 $ 18.10   $ 20.01
Vesting period 4 years 4 years   4 years
Granted shares of restricted stock 200,000 70,000    
Fair value restricted stock $ 24.62 $ 18.10    
Stock options exercisable [Member]
       
Share-based Compensation (Textual) [Abstract]        
Percentage of stock options to be vested 75.00% 75.00%   75.00%
Remaining percentage of stock options to be vested 25.00% 25.00%   25.00%
Restricted common stock [Member]
       
Share-based Compensation (Textual) [Abstract]        
Vesting period 4 years 4 years 4 years 4 years
Granted shares of restricted stock 161,516 121,564 31,302 382,050
Fair value restricted stock $ 24.62 $ 18.10 $ 19.17 $ 20.01
Vested Quarterly Over One Year [Member]
       
Share-based Compensation (Textual) [Abstract]        
Granted shares of restricted stock       74,760
Fair value restricted stock       $ 20.01
One Year Vesting [Member]
       
Share-based Compensation (Textual) [Abstract]        
Granted shares of restricted stock       4,365
Fair value restricted stock       $ 21.22