Fair Value Measurements (Fair Values And Related Carrying Values Of Financial Instruments That Are Not Required To Be Remeasured At Fair Value) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Accounts receivable, net	$ 5,894	$ 5,793
Notes receivable, net	656	792
Debt, excluding capital lease obligations	(10,994)	(12,136)
Accounts payable	(9,273)	(8,406)
Residual value and credit guarantees	(4)	(8)
Contingent repurchase commitments	(7)	(7)
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Accounts receivable, net	5,919	5,690
Notes receivable, net	711	836
Debt, excluding capital lease obligations	(13,111)	(14,099)
Accounts payable	(9,264)	(8,396)
Residual value and credit guarantees	(3)	(9)
Contingent repurchase commitments	(10)	(4)
Level 2 [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Accounts receivable, net	5,919
Notes receivable, net	711
Debt, excluding capital lease obligations	(13,042)
Accounts payable	(9,264)
Level 3 [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt, excluding capital lease obligations	(69)
Residual value and credit guarantees	(3)
Contingent repurchase commitments	$ (10)