Fair Value Fair Value (Details 2) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Fair Value of Financial Instruments [Line Items]
Notes receivable, excluding capital leases	$ 5	$ 5
Short-term borrowings - affiliates	51	80
Other Short-term Borrowings	0	130
Long-term debt	5,197	4,963
Fair Value, Inputs, Level 1 [Member]
Fair Value of Financial Instruments [Line Items]
Notes receivable, excluding capital leases	0	0
Short-term borrowings affiliates	0	0
Short-term Debt, Fair Value	0	0
Long-term debt	0	0
Fair Value, Inputs, Level 2 [Member]
Fair Value of Financial Instruments [Line Items]
Notes receivable, excluding capital leases	0	0
Short-term borrowings affiliates	0	0
Short-term Debt, Fair Value	0	130
Long-term debt	5,111	5,021
Fair Value, Inputs, Level 3 [Member]
Fair Value of Financial Instruments [Line Items]
Notes receivable, excluding capital leases	5	5
Short-term borrowings affiliates	51	80
Short-term Debt, Fair Value	0	0
Long-term debt	$ 711	$ 620