Indebtedness (Details) (USD $)	1 Months Ended	12 Months Ended							12 Months Ended			12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended				6 Months Ended	12 Months Ended
	Aug. 31, 2011	Dec. 31, 2011 Swaps	Dec. 31, 2009	Dec. 31, 2010	Dec. 31, 2011 Revolving Credit Facility with commercial bank [Member]	Dec. 31, 2011 Revolving Credit Facility Maturing On September 2016 [Member]	Dec. 31, 2011 Revolving Credit Facility Expiring On July 2012 [Member]	Dec. 31, 2011 Revolving Credit Facility Expiring On March 2013 [Member]	Dec. 31, 2011 Interest Rate Swaps [Member]	Dec. 31, 2011 6.5% Senior Notes due November 2013 with an effective interest rate of 6.73% [Member]	Dec. 31, 2010 6.5% Senior Notes due November 2013 with an effective interest rate of 6.73% [Member]	Dec. 31, 2011 6.0% Notes due June 2018 with an effective interest rate of 6.29% [Member]	Dec. 31, 2010 6.0% Notes due June 2018 with an effective interest rate of 6.29% [Member]	Dec. 31, 2011 7.5% Senior Notes due November 2018 with an effective interest rate of 7.61%	Dec. 31, 2010 7.5% Senior Notes due November 2018 with an effective interest rate of 7.61%	Dec. 31, 2011 3.2% Senior Notes due August 2021 with an effective interest rate of 3.32% [Member]	Dec. 31, 2010 3.2% Senior Notes due August 2021 with an effective interest rate of 3.32% [Member]	Dec. 31, 2011 8.55% Debentures due June 2024 with an effective interest rate of 8.76% [Member]	Dec. 31, 2010 8.55% Debentures due June 2024 with an effective interest rate of 8.76% [Member]	Dec. 31, 2011 6.875% Notes due January 2029 with an effective interest rate of 7.08% [Member]	Dec. 31, 2010 6.875% Notes due January 2029 with an effective interest rate of 7.08% [Member]	Dec. 31, 2011 5.125% Notes due September 2040 with an effective interest rate of 5.22% [Member]	Dec. 31, 2010 5.125% Notes due September 2040 with an effective interest rate of 5.22% [Member]	Dec. 31, 2011 Other debt [Member]	Dec. 31, 2010 Other debt [Member]	Jun. 30, 2011 5.75% Notes due June 2011 with an effective interest rate of 5.86% [Member]	Dec. 31, 2011 5.75% Notes due June 2011 with an effective interest rate of 5.86% [Member]	Dec. 31, 2010 5.75% Notes due June 2011 with an effective interest rate of 5.86% [Member]
Total debt, net of unamortized discount and debt issuance costs
Total debt		$ 4,069,000,000		$ 3,885,000,000
Less short-term debt and current portion of long-term debt		224,000,000		331,000,000
Long-term debt		3,845,000,000		3,554,000,000						0	522,000,000	265,000,000	267,000,000	743,000,000	742,000,000	742,000,000	0	148,000,000	148,000,000	393,000,000	393,000,000	1,479,000,000	1,479,000,000	299,000,000	80,000,000		0	254,000,000
Face value of new debt issued		4,069,000,000		3,885,000,000												750,000,000
Repayment of long-term debt		813,000,000	525,000,000							563,000,000																250,000,000	250,000,000
Interest rate on notes		6.50%								6.50%		6.00%		7.50%		3.20%		8.55%		6.875%		5.125%				5.75%	5.75%
Effective interest rate										6.73%		6.29%		7.61%		3.32%		8.76%		7.08%		5.22%					5.86%
Maturity date of Notes										Nov. 01, 2013		Jun. 01, 2018		Nov. 01, 2018		Aug. 01, 2021		Jun. 01, 2024		Jan. 01, 2029		Sep. 01, 2040					Jun. 01, 2011
Gain from the termination of interest rate swap agreements									25,000,000
Line Of Credit Facility [Line Items]
Committed revolving credit facility						2,500,000,000	500,000,000	1,200,000,000
Borrowing Under Committed revolving credit facility					0
Indebtedness (Textual) [Abstract]
Net proceeds from Senior notes after deducting the underwriting discount and expense approximately	742,000,000
Premium paid in connection with redemption of notes		63,000,000
Loss on early extinguishment of debt		(40,000,000)
Commercial paper can be issued under commercial paper program		2,500,000,000
Maximum maturities of commercial paper issued		270 days
Commercial paper		130,000,000
Number of swap agreements		2
Maturities of debt
Maturities of debt 2012		224,000,000
Maturities of debt 2013		8,000,000
Maturities of debt 2014		10,000,000
Maturities of debt 2015		13,000,000
Maturities of debt 2016		15,000,000
Maturities of debt thereafter		$ 3,799,000,000