v2.4.0.6
Retirement Plans (Schedule Of Expense Related To These Defined Contribution Plans) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Defined Benefit Plan Disclosure [Line Items]      
Expense related to defined contribution plans $ 54 $ 49 $ 49
401 (k) Plan [Member]
     
Defined Benefit Plan Disclosure [Line Items]      
Expense related to defined contribution plans 33 32 34
Canadian Pension And Savings Plans [Member]
     
Defined Benefit Plan Disclosure [Line Items]      
Expense related to defined contribution plans $ 21 $ 17 $ 15