Certain Employee Benefit and Stock-Based Compensation Plans (Summary of Components of Net Periodic Benefit Cost) (Details) (USD $) In Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Qualified Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 24	$ 25	$ 71	$ 77
Interest cost	49	51	147	152
Expected return on plan assets	(75)	(71)	(224)	(214)
Amortization of prior service cost	(2)	(2)	(6)	(6)
Amortization of actuarial losses	5	8	14	25
Net periodic cost (benefit)	1	11	2	34
Nonqualified Retirement Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1	3	2
Interest cost	3	3	10	10
Amortization of actuarial losses	1	1	3	3
Net periodic cost (benefit)	5	5	16	15
Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1	5	4
Interest cost	5	5	14	15
Amortization of prior service cost	(1)		(2)	(2)
Net periodic cost (benefit)	$ 5	$ 6	$ 17	$ 17