Commitments And Contingencies (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Future Minimum Lease Payments For Operating Leases [Abstract]
Total minimum operating lease payments	$ 4,200
Personal Injury [Member]
Liability Activity [Abstract]
Commitments and contingencies, beginning balance at January 1	368	426
Accruals	89	99
Changes in estimates for prior years	(40)	(51)
Payments	(69)	(83)
Commitments and contingencies, ending balance at September 30	348	391
Commitments and contingencies, current portion, ending balance at September 30	97	140
Asserted And Unasserted Claims [Abstract]
Percent of liability recorded related to asserted claims	90.00%
Percent of liability recorded related to unasserted claims	10.00%
Reasonably possible outcome of related claims, range minimum	348
Reasonably possible outcome of related claims, range maximum	377
Asbestos [Member]
Liability Activity [Abstract]
Commitments and contingencies, beginning balance at January 1	147	162
Accruals	0	0
Payments	(5)	(7)
Commitments and contingencies, ending balance at September 30	142	155
Commitments and contingencies, current portion, ending balance at September 30	9	11
Asserted And Unasserted Claims [Abstract]
Percent of liability recorded related to asserted claims	22.00%
Percent of liability recorded related to unasserted claims	78.00%
Environmental [Member]
Liability Activity [Abstract]
Commitments and contingencies, beginning balance at January 1	172	213
Accruals	35	26
Payments	(32)	(61)
Commitments and contingencies, ending balance at September 30	175	178
Commitments and contingencies, current portion, ending balance at September 30	49	49
Environmental [Abstract]
Sites identified which we are or may be liable for remediation costs	289
Sites subject of actions taken by the U.S. government	32
Sites on the Superfund National Priorities List	17
Percent of liability discounted	0		less than 1%
Environmental liability discount rate			2.00%
Guarantees [Member]
Guarantees [Abstract]
Maximum potential amount of guarantee payments	309
Recorded liability for fair value of guarantees	$ 2		$ 3
Expiration year of final guarantee	The final guarantee expires in 2022.