v2.4.0.6
Employee Benefits, Components of Net Periodic Benefit Cost (Details) (USD $)
In Millions, unless otherwise specified
 3 Months Ended
Mar. 31, 2012
Mar. 31, 2011
Pension benefits qualified [Member]
    
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]    
Service cost $ 0 $ 1
Interest cost 128 130
Expected return on plan assets (162) (189)
Amortization of net actuarial loss 33 21
Amortization of prior service credit 0 0
Settlements 1 2
Net periodic benefit cost (income) 0 (35)
Pension benefits non-qualified [Member]
    
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]    
Service cost 0 0
Interest cost 8 9
Expected return on plan assets 0 0
Amortization of net actuarial loss 3 2
Amortization of prior service credit 0 0
Settlements 0 0
Net periodic benefit cost (income) 11 11
Other benefits [Member]
    
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]    
Service cost 3 3
Interest cost 15 18
Expected return on plan assets (9) (10)
Amortization of net actuarial loss 0 0
Amortization of prior service credit (1) (1)
Settlements 0 0
Net periodic benefit cost (income) $ 8 $ 10