Retirement Benefits and Trusteed Assets (Details) (USD $) In Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 15	$ 16	$ 52	$ 48
Interest cost	51	51	152	152
Expected return on plan assets	(62)	(65)	(185)	(194)
Defined Benefit Plan Amortization [Abstract]
Net actuarial loss	41	25	107	75
Prior service cost (credit)	0	1	2	3
Net transition liability	0	0	0	0
Special termination benefits	0	0	2
Net periodic benefit cost	45	28	130	84
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	14	15	48	46
Interest cost	28	31	90	94
Expected return on plan assets	(24)	(18)	(71)	(56)
Defined Benefit Plan Amortization [Abstract]
Net actuarial loss	12	13	42	40
Prior service cost (credit)	(7)	(1)	(20)	(3)
Net transition liability	1	1	2	2
Special termination benefits	0	0	0	0
Net periodic benefit cost	$ 24	$ 41	$ 91	$ 123