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Share-Based Payments (General Descriptions) (Details) (USD $)
In Millions, except Share data, unless otherwise specified
9 Months Ended 9 Months Ended
Sep. 30, 2013
Sep. 30, 2012
Sep. 30, 2013
Common Class A [Member]
Dec. 31, 2012
Common Class A [Member]
Jun. 20, 2008
Common Class A [Member]
Jun. 25, 2004
Common Class A [Member]
Sep. 30, 2013
Director [Member]
Sep. 30, 2013
Employees [Member]
Jun. 25, 2004
1995 Plan [Member]
Common Class A [Member]
Jun. 20, 2008
2008 Plan [Member]
Common Class A [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                    
Common stock, par value     $ 1 $ 1 $ 1.00 $ 1.00        
Share-based payments, number of shares authorized under plans                 300,000 300,000
Annual vesting percentage             20.00% 20.00%    
Requisite service period of awards             1 year 3 years    
Expiration period of awards 10 years                  
Awards issued during the period (in shares) 0 0                
Period in force, from which option holders may elect to sell back acquired shares 90 days                  
Pre-tax compensation cost (benefit) recognized $ 4.0 $ 0.4                
Compensation cost (benefit), tax expense (benefit) 1.4 0.1                
Compensation cost related to nonvested options not yet recognized $ 1.9                  
Weighted average period over which the compensation is expected to be recognized 1 year 9 months 24 days