Annual report pursuant to Section 13 and 15(d)

Pensions And Other Postretirement Benefits (Other Potential Benefit Obligations) (Details)

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Pensions And Other Postretirement Benefits (Other Potential Benefit Obligations) (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Pension Benefits [Member]
     
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets $ 744.1 $ 734.3 $ 483.4
Benefit obligation 1,141.4 1,022.3 750.8
Underfunded status of plan 397.3 288.0  
Additional shutdown and early retirement benefits 40.0    
Other Benefits [Member]
     
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 193.5 174.2 136.7
Benefit obligation 488.4 440.2 333.0
Underfunded status of plan 294.9 266.0  
Additional shutdown and early retirement benefits $ 19.3