Pension and Other Postretirment Benefits (Details) (USD $) In Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Pension And Other Postretirement Footnote Text Details [Abstract]
Decrease to postretirement benefits liability adjustment pre-tax			$ 20
Decrease to postretirement benefits liability adjustement after-tax			13
Defined Benefit Pension Member
Pension And Other Postretirement Benefits Table [Line Items]
Service cost	0	0	1	1
Interest cost	57	61	171	181
Expected long-term return on plan assets	(67)	(63)	(200)	(189)
Amortization of net loss from past experience	10	7	29	21
Amortization of prior service cost	0	0	0	0
Net pension cost	0	5	1	14
Pension And Other Postretirement Footnote Text Details [Abstract]
Required domestic pension plan contributions			77
Total domestic pension plan contributions			231
Voluntary contributions to the pension plan that may be made during the remainder of the year	19		19
Voluntary Domestic Pension Plan Contributions			154
Other Postretirement Benefit Plans Defined Benefit Member
Pension And Other Postretirement Benefits Table [Line Items]
Service cost	0	0	1	1
Interest cost	5	7	15	17
Expected long-term return on plan assets	0	(1)	0	(1)
Amortization of net loss from past experience	0	0	0	0
Amortization of prior service cost	(4)	(5)	(12)	(14)
Net pension cost	$ 1	$ 1	$ 4	$ 3