Debt (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2011	Dec. 31, 2010
Available and unused lines of credit	$ 2,744.7	$ 2,610.4
Short-term borrowings	63.9	50.2
Long-term notes payable, carrying amount	2,502.1	2,501.5
Long-term notes payable, unamortized discount on Senior Notes	(8.1)	(8.7)
Fair value hedge adjustment on Senior Notes due 2016	(4.2)	(26.3)
Total long-term notes payable	2,489.8	2,466.5
Less current portion	1.8	1.4
LONG-TERM NOTES PAYABLE	2,488.0	2,465.1
Total convertible debt	659.4	659.5
Less current portion	0	0
CONVERTIBLE DEBT	659.4	659.5
Credit facility expiring December 2013 [Member]
Credit facility, maximum borrowing Capacity	2,000.0
Credit facility, expiration date	December 9, 2013
Available and unused lines of credit	2,000.0	2,000.0
Credit facility expiring December 2013 [Member] | Commercial Paper [Member]
Credit facility, maximum borrowing Capacity	1,500.0
Uncommitted lines of credit [Member]
Available and unused lines of credit	744.7	610.4
5.90% Senior Notes due April 15, 2016 [Member]
Long-term notes payable, carrying amount	1,000.0	1,000.0
Interest rate	5.90%	5.90%
Maturity date	Apr. 15, 2016	Apr. 15, 2016
6.25% Senior Notes due July 15, 2019 [Member]
Long-term notes payable, carrying amount	500.0	500.0
Interest rate	6.25%	6.25%
Maturity date	Jul. 15, 2019	Jul. 15, 2019
4.45% Senior Notes due August 15, 2020 [Member]
Long-term notes payable, carrying amount	1,000.0	1,000.0
Interest rate	4.45%	4.45%
Maturity date	Aug. 15, 2020	Aug. 15, 2020
Other notes and loans [Member]
Long-term notes payable, carrying amount	2.1	1.5
Convertible Notes - due February 7, 2031 [Member]
Total convertible debt	0	0.1
Interest rate		0.00%
Maturity date		Feb. 07, 2031
Convertible Notes - due July 31, 2032 [Member]
Total convertible debt	252.7	252.7
Interest rate	0.00%	0.00%
Maturity date	Jul. 31, 2032	Jul. 31, 2032
Convertible Notes - due June 15, 2033 [Member]
Total convertible debt	0.1	0.1
Interest rate	0.00%	0.00%
Maturity date	Jun. 15, 2033	Jun. 15, 2033
Convertible Notes - due July 1, 2038 [Member]
Total convertible debt	406.6	406.6
Interest rate	0.00%	0.00%
Maturity date	Jul. 01, 2038	Jul. 01, 2038
Interest Rate Swaps on 2016 Notes [Member]
Interest rate swaps, amount of hedged item	1,000.0
Interest rate swaps, fair value	$ 6.5	$ 24.2
Interest rate swaps, variable interest rate	The variable interest rate we pay is based on the one-month and three-month U.S. LIBOR rate, flat.
Interest rate swaps, fixed interest rate	1.766%
Maturity date	Apr. 15, 2016