Annual report pursuant to Section 13 and 15(d)

Shareholders' Equity, Stock Options and Net Income per Share - Non-employee Director Non-vested Shares (Details)

v2.4.0.6
Shareholders' Equity, Stock Options and Net Income per Share - Non-employee Director Non-vested Shares (Details) (USD $)
In Thousands, except Share data, unless otherwise specified
 12 Months Ended
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Dec. 31, 2007
Dec. 31, 2006
Non-Employee Directors - Non-Vested Shares [Line Items]          
Non-employee director, non-vested share vesting period 3 years        
Share-based compensation $ 5,971 $ 6,284 $ 6,754    
Nonemployee Director Nonvested Shares Granted Member
          
Non-Employee Directors - Non-Vested Shares [Line Items]          
Non-employee director, non-vested share vesting period 1     3  
Non-vested shares or deferred stock units issued 23,809 19,131 30,870 375 13,500
Weighted average grant date fair value of non-vested shares $ 32.58 $ 29.27 $ 18.14 $ 30.88 $ 36.27
Number of non-vested shares that vested during the year 19,131 30,995 20,017    
Grant date fair value of shares that vested during the year 615 892 700    
Non-vested shares granted to non-employee directors that had not vested at year end 23,809        
Share-based compensation 707 563 617    
Tax benefit related to share-based compensation expense 274 226 261    
Unrecognized compensation cost $ 271