v2.4.0.6
Retirement Plans (Narrative) (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]      
Value of trusts established for certain supplemental plans $ 32 $ 36  
Employer contributions transferred from trusts 8 8  
Pension plan contributions 454    
Effect on benefit obligation with a 1% increase or decrease 2    
Effect on benefit obligation with a 1% increase or decrease 1    
Pension benefits to be funded from the trust 9    
Postretirement benefits expected to be funded from cash and cash equivalents 3    
Pension Benefits [Member]
     
Defined Benefit Plan Disclosure [Line Items]      
Accumulated benefit obligation 1,200 1,000  
Pension plan contributions 454 66  
Other Postretirement Benefits [Member]
     
Defined Benefit Plan Disclosure [Line Items]      
Accumulated benefit obligation 37 43 64
Pension plan contributions $ 7 $ 4  
Defined benefit plan health care cost trend rate assumed for next fiscal year 8.20%    
Defined benefit plan ultimate health care cost trend rate 5.00%