Fair Value Fair Value (Details 4) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Fair Value of Financial Instruments [Line Items]
Notes Receivable Excudling Capital Leases	$ 37	$ 39
Dividends payable	116	107
Short-term Debt	271	240
Long-term Debt	7,729	7,813
Fair Value, Inputs, Level 1 [Member]
Fair Value of Financial Instruments [Line Items]
Notes Receivable, Fair Value Disclosure	0	0
Dividends Payable Fair Value Disclosure	116	107
Short-term Debt, Fair Value	0	0
Long-term Debt, Fair Value	436	507
Fair Value, Inputs, Level 2 [Member]
Fair Value of Financial Instruments [Line Items]
Notes Receivable, Fair Value Disclosure	0	0
Dividends Payable Fair Value Disclosure	0	0
Short-term Debt, Fair Value	271	240
Long-term Debt, Fair Value	7,067	7,453
Fair Value, Inputs, Level 3 [Member]
Fair Value of Financial Instruments [Line Items]
Notes Receivable, Fair Value Disclosure	37	39
Dividends Payable Fair Value Disclosure	0	0
Short-term Debt, Fair Value	0	0
Long-term Debt, Fair Value	$ 738	$ 933