Annual report pursuant to Section 13 and 15(d)

Stock Based Compensation (Narrative) (Details)

v2.4.0.6
Stock Based Compensation (Narrative) (Details) (USD $)
12 Months Ended
Dec. 31, 2011
years
Dec. 31, 2010
Dec. 31, 2009
Dec. 31, 2008
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Shares authorized for issuance under the Plan 1,500,000      
Share-based compensation exercise period 10      
Number of shares available for grant for future issuance 811,436      
Number of shares for initial granting of options 3,500      
Number of shares for annual granting of options 2,000      
Percentage of annual fees in the form on non-vested shares 80.00%      
Non-vested shares issued to outside directors 3,116      
Common stock available for future issuance 150,000      
Share-based compensation, vesting period, minimum (in years) four      
Share-based compensation, vesting period, maximum (in years) eight      
Non-employee Plan, share-based compensation, vesting period (in years) one      
Shares outstanding under the Plans, non-vested shares 246,634 192,776 154,593 130,807
Intrinsic value of stock options exercised $ 396,532 $ 382,576 $ 50,188  
Total unrecognized compensation 700,000      
Cost recognition, weighted-average period 3.6      
Weighted average remaining contractual life of all exercisable options (in years) 5.7      
Weighted average remaining contractual life of all options (in years) 6.2      
Shares of non-vested stock issued to employees 533,486      
Shares granted under performance plan 106,602 78,152 59,590  
Non-vested stock, aggregate fair value 3,700,000      
Compensation expense 1,500,000 1,300,000 1,400,000  
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period one      
Fair market value of the non-vested stock on the date of grant $ 35.02 $ 37.03 $ 29.70  
Shares outstanding under the Plans 364,268 387,318 397,468 360,688
Stock Options [Member]
       
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Common stock available for future issuance 115,684      
Common shares options outstanding 47,005      
Shares outstanding under the Plans 317,263      
Non-Vested Shares [Member]
       
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Share-based compensation, vesting period, minimum (in years) one      
Share-based compensation, vesting period, maximum (in years) nine      
Shares outstanding under the Plans, non-vested shares 17,521      
Total unrecognized compensation 7,800,000      
Cost recognition, weighted-average period 4.1      
Shares of non-vested stock issued to employees 106,602      
Non-vested stock, aggregate fair value 2,000,000 1,500,000 1,500,000  
Performance-Based Vesting Restricted Stock [Member]
       
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Total unrecognized compensation 1,200,000      
Cost recognition, weighted-average period 2      
Shares granted under performance plan 42,040      
Compensation expense 100,000      
Deferred Compensation Plan For Directors [Member]
       
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Shares outstanding under Deferred Compensation Plan 45,025      
Maximum [Member]
       
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Fair market value of the non-vested stock on the date of grant $ 41.07      
Minimum [Member]
       
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Fair market value of the non-vested stock on the date of grant $ 28.66      
Director [Member]
       
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Deferred compensation expense $ 200,000 $ 200,000 $ 100,000