Debt (Details) (USD $)	9 Months Ended			9 Months Ended			9 Months Ended			0 Months Ended			9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010	Sep. 30, 2011 Interest Rate Swaps on 2016 Notes [Member]	Aug. 18, 2011 Interest Rate Swaps on 2016 Notes [Member]	Dec. 31, 2010 Interest Rate Swaps on 2016 Notes [Member]	Sep. 30, 2011 Credit facility expiring December 2013 [Member]	Dec. 31, 2010 Credit facility expiring December 2013 [Member]	Sep. 30, 2011 Credit facility expiring December 2013 [Member] Commercial Paper [Member]	Oct. 12, 2011 Credit Facility expiring October 2016 [Domain]	Sep. 30, 2011 Uncommitted lines of credit [Member]	Dec. 31, 2010 Uncommitted lines of credit [Member]	Sep. 30, 2011 5.90% Senior Notes due April 15, 2016 [Member]	Dec. 31, 2010 5.90% Senior Notes due April 15, 2016 [Member]	Sep. 30, 2011 6.25% Senior Notes due July 15, 2019 [Member]	Dec. 31, 2010 6.25% Senior Notes due July 15, 2019 [Member]	Sep. 30, 2011 4.45% Senior Notes due August 15, 2020 [Member]	Dec. 31, 2010 4.45% Senior Notes due August 15, 2020 [Member]	Sep. 30, 2011 Other notes and loans [Member]	Dec. 31, 2010 Other notes and loans [Member]	Sep. 30, 2011 Convertible Notes - due February 7, 2031 [Member]	Dec. 31, 2010 Convertible Notes - due February 7, 2031 [Member]	Sep. 30, 2011 Convertible Notes - due July 31, 2032 [Member]	Dec. 31, 2010 Convertible Notes - due July 31, 2032 [Member]	Sep. 30, 2011 Convertible Notes - due June 15, 2033 [Member]	Dec. 31, 2010 Convertible Notes - due June 15, 2033 [Member]	Sep. 30, 2011 Convertible Notes - due July 1, 2038 [Member]	Dec. 31, 2010 Convertible Notes - due July 1, 2038 [Member]
Credit facility, maximum borrowing Capacity							$ 2,000,000,000		$ 1,500,000,000	$ 2,500,000,000
Credit facility, expiration date							December 9, 2013			October 12, 2016
Available and unused lines of credit	3,031,500,000		2,610,400,000				2,000,000,000	2,000,000,000			1,031,500,000	610,400,000
Short-term borrowings	16,400,000		50,200,000
Long-term notes payable, carrying amount	2,501,400,000		2,501,500,000										1,000,000,000	1,000,000,000	500,000,000	500,000,000	1,000,000,000	1,000,000,000	1,400,000	1,500,000
Long-term notes payable, unamortized discount on Senior Notes	(7,900,000)		(8,700,000)
Fair value hedge adjustment on Senior Notes due 2016	0		(26,300,000)
Deferred gain from termination of interest rate swaps on Senior Notes due 2016	32,300,000		0		33,200,000
Total long-term notes payable	2,525,800,000		2,466,500,000
Less current portion	1,000,000		1,400,000
LONG-TERM NOTES PAYABLE	2,524,800,000		2,465,100,000
Total convertible debt	659,400,000		659,500,000																		0	100,000	252,700,000	252,700,000	100,000	100,000	406,600,000	406,600,000
Less current portion	0		0
CONVERTIBLE DEBT	659,400,000		659,500,000
Interest rate swaps, amount of hedged item						1,000,000,000
Proceeds from termination of interest rate swaps	38,800,000	0		38,800,000
Interest rate swaps, fair value						$ 24,200,000
Interest rate													5.90%
Maturity date													Apr. 15, 2016