v2.4.0.6
Employee Benefit Plans (Components of Net Periodic Benefit Expense) (Details) (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Curtailment gain $ 0 $ 0 $ (54)
Pension
      
Service cost, benefits earned during the period 26 27 99
Interest cost on projected benefit obligation 156 158 152
Expected return on plan assets (110) (131) (128)
Net amortization of prior service costs 0 0 (4)
Net amortization of actuarial loss 27 17 24
Curtailment gain 0 0 (50)
Settlement loss 0 1 3
Net periodic benefit expense 99 72 96
Postretirement
      
Service cost, benefits earned during the period 4 4 7
Interest cost on projected benefit obligation 7 8 11
Expected return on plan assets 0 0 0
Net amortization of prior service costs (14) (14) (3)
Net amortization of actuarial loss 2 2 1
Curtailment gain 0 0 (4)
Settlement loss 0 0 0
Net periodic benefit expense $ (1) $ 0 $ 12