Long-Term Debt and Credit Facilities (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Debt Instrument [Line Items]
Total debt	$ 5,176	$ 4,776
Less: Current portion of long-term debt	(250)	(346)
Long-term Debt, Excluding Current Maturities	4,926	4,430
Short-term Bank Loans and Notes Payable	54	34
Weighted-average interest rate on short term borrowings (in hundredths)	1.00%	0.90%
Scheduled maturities of long-term debt [Abstract]
2012	250
2013	887
2014	494
2015	254
2016	678
Thereafter	2,170
Notes Payable, Other Payables [Member]
Debt Instrument [Line Items]
Weighted average interest rate (in hundredths)	2.10%
Maturity date range, start	Dec. 31, 2013
Maturity date range, end	Dec. 31, 2078
Total debt	4,733	4,089
Notes Payable to Banks [Member]
Debt Instrument [Line Items]
Weighted average interest rate (in hundredths)	0.00%
Total debt	0	16
Commercial Paper [Member]
Debt Instrument [Line Items]
Weighted average interest rate (in hundredths)	0.10%
Maturity date	2013
Total debt	$ 443	$ 671