Pension and Other Postretirment Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Pension And Other Postretirement Footnote Text Details [Abstract]
Decrease to postretirement benefits liability adjustment pre-tax	$ 17
Decrease to postretirement benefits liability adjustement after-tax	11
Total domestic pension plan contributions	20
Required domestic pension plan contributions	20
Voluntary Domestic Pension Plan Contributions	0
Expected additional contributions to Company's pension plans for the remainder of the year	230
Defined Benefit Pension Member
Pension And Other Postretirement Benefits Table [Line Items]
Service cost	1	1
Interest cost	49	57
Expected long-term return on plan assets	(67)	(65)
Amortization of net loss from past experience	15	9
Amortization of prior service cost	0	0
Settlement loss (gain)	6	0
Net pension cost	4	2
Other Postretirement Benefit Plans Defined Benefit Member
Pension And Other Postretirement Benefits Table [Line Items]
Service cost	0	0
Interest cost	4	5
Expected long-term return on plan assets	0	0
Amortization of net loss from past experience	0	0
Amortization of prior service cost	(3)	(4)
Settlement loss (gain)	0	0
Net pension cost	$ 1	$ 1