Pension and Other Postretirment Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Pension And Other Postretirement Footnote Text Details [Line Items]
Decrease to postretirement benefits liability adjustment pre-tax			$ 66
Decrease to postretirement benefits liability adjustement after-tax			44
Total domestic pension plan contributions			226
Required domestic pension plan contributions			90
Voluntary Domestic Pension Plan Contributions			136
Expected additional contributions to Company's pension plans for the remainder of the year	24		24
Defined Benefit Pension Member
Pension And Other Postretirement Benefits Table [Line Items]
Service cost	1	0	2	1
Interest cost	50	57	149	171
Expected long-term return on plan assets	(69)	(67)	(203)	(200)
Amortization of net loss from past experience	15	10	45	29
Amortization of prior service cost	0	0	0	0
Settlement loss (gain)	0	0	6	0
Net pension cost	(3)	0	(1)	1
Other Postretirement Benefit Plans Defined Benefit Member
Pension And Other Postretirement Benefits Table [Line Items]
Service cost	0	0	1	1
Interest cost	4	5	12	15
Expected long-term return on plan assets	0	0	0	0
Amortization of net loss from past experience	0	0	0	0
Amortization of prior service cost	(3)	(4)	(9)	(12)
Settlement loss (gain)	0	0	0	0
Net pension cost	$ 1	$ 1	$ 4	$ 4