Short-Term Debt (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Short term borrowings
Commercial Paper	$ 2,498	$ 2,471
Notes payable to banks and others with originating terms of one year or less	40	43
Current maturities of long-term debt	17	33
Current maturities of long-term capital leases	54	81
Redeemable long term obligations - Long-Term Debt	3,317	2,943
Redeemable long term obligations - Capital Leases	14	16
Subtotal	5,940	5,587
Reclassified to long-term debt	(5,600)	(5,400)
Total short-term debt	$ 340	$ 187