SHORT-TERM BORROWINGS AND LONG-TERM DEBT (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Long-Term Debt
Principal value of long-term debt obligations	$ 1,500.0		$ 1,500.0		$ 1,500.0
Basis adjustment for fair value of outstanding interest rate swaps					20.1
Unamortized basis adjustment for terminated interest rate swaps	37.7		37.7		16.5
Unamortized bond discount	(3.6)		(3.6)		(4.1)
Long-term debt	1,534.1		1,534.1		1,532.5
Long-term debt - estimated fair value	1,637.6		1,637.6
Interest expense	15.6	13.3	44.5	39.2
Interest income	2.5	1.3	6.1	3.5
3.50% Notes due 2014
Long-Term Debt
Stated rate (as a percent)	3.50%		3.50%		3.50%
Principal value of long-term debt obligations	500.0		500.0		500.0
4.90% Notes due 2019
Long-Term Debt
Stated rate (as a percent)	4.90%		4.90%		4.90%
Principal value of long-term debt obligations	700.0		700.0		700.0
5.90% Notes due 2039
Long-Term Debt
Stated rate (as a percent)	5.90%		5.90%		5.90%
Principal value of long-term debt obligations	$ 300.0		$ 300.0		$ 300.0