SHORT-TERM BORROWINGS AND LONG-TERM DEBT (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Long-Term Debt
Principal value of long-term debt obligations	$ 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	35.3	16.5
Unamortized bond discount	(3.4)	(4.1)
Long-term debt	1,531.9	1,532.5
Long-term debt - estimated fair value	1,647.3
Interest expense, net of amounts related to interest rate swaps	60.2	53.2	95.9
Interest income	8.0	4.6	3.3
Interest payments, net of amounts related to interest rate swaps	61.4	51.5	131.0
3.50% Notes due 2014
Long-Term Debt
Stated rate (as a percent)	3.50%
Principal value of long-term debt obligations	500.0	500.0
4.90% Notes due 2019
Long-Term Debt
Stated rate (as a percent)	4.90%
Principal value of long-term debt obligations	700.0	700.0
5.90% Notes due 2039
Long-Term Debt
Stated rate (as a percent)	5.90%
Principal value of long-term debt obligations	$ 300.0	$ 300.0