Fair Value Fair Value (Details 4) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Fair Value of Financial Instruments [Line Items]
Notes Receivable Excudling Capital Leases	$ 36	$ 39
Dividends Payable, Current	229	107
Short-term Debt	216	240
Long-term Debt	7,671	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	229	107
Short-term Debt, Fair Value	0	0
Long-term Debt, Fair Value	487	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	216	240
Long-term Debt, Fair Value	6,556	7,453
Fair Value, Inputs, Level 3 [Member]
Fair Value of Financial Instruments [Line Items]
Notes Receivable, Fair Value Disclosure	36	39
Dividends Payable Fair Value Disclosure	0	0
Short-term Debt, Fair Value	0	0
Long-term Debt, Fair Value	$ 1,008	$ 933