Pension and Other Employee Benefits (Schedule of Change in Plan Assets) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Defined Pension Benefits [Member]
   
Fair value of plan assets, total $ 15,552 $ 15,099
Actual return (loss) on plan assets 1,868 (148)
Company contributions 1,221 1,828
Plan participants' contributions 18 19
Plan settlements (3) 0
Foreign exchange gain (loss) 27 (1)
Benefits paid (1,233) (1,245)
Net transfer in 0 0
Fair value of plan assets, total 17,450 15,552
Other Benefits [Member]
   
Fair value of plan assets, total 396 433
Actual return (loss) on plan assets 46 (3)
Company contributions 19 18
Plan participants' contributions 44 46
Plan settlements 0 0
Foreign exchange gain (loss) 0 0
Benefits paid (97) (98)
Net transfer in 0 0
Fair value of plan assets, total $ 408 $ 396