v2.4.0.8
Employee Benefits, Components of Net Periodic Benefit Cost (Details) (USD $)
In Millions, unless otherwise specified
 3 Months Ended 6 Months Ended
Jun. 30, 2013
Jun. 30, 2012
Jun. 30, 2013
Jun. 30, 2012
Other Changes In Plan Assets And Benefit Obligations Recognized In Other Comprehensive Income [Abstract]        
Net actuarial loss (gain) $ (772) $ 12 $ (778) $ 17
Total recognized in other comprehensive income (885) (28) (940) (59)
Pension Benefits Qualified [Member]
        
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]        
Service cost 0 1 0 1
Interest cost 113 128 226 256
Expected return on plan assets (170) (163) (341) (325)
Amortization of net actuarial loss 42 33 84 66
Amortization of prior service credit     0 0
Settlement 68 0 68 1
Net periodic benefit cost (income) 53 (1) 37 (1)
Pension Benefits Nonqualified [Member]
        
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]        
Service cost 0 0 0 0
Interest cost 7 8 14 16
Expected return on plan assets 0 0 0 0
Amortization of net actuarial loss 3 2 7 5
Amortization of prior service credit     0 0
Settlement 0 5 4 5
Net periodic benefit cost (income) 10 15 25 26
Other benefits [Member]
        
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]        
Service cost 2 3 5 6
Interest cost 12 15 24 30
Expected return on plan assets (9) (8) (18) (17)
Amortization of net actuarial loss 0 0 0 0
Amortization of prior service credit     (1) (1)
Settlement 0 (1) 0 (1)
Net periodic benefit cost (income) $ 5 $ 9 $ 10 $ 17