DEBT - CREDIT FACILITIES (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			12 Months Ended				3 Months Ended
	Mar. 31, 2011	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011 Revolving Credit Facility [Member]	Dec. 31, 2011 Term loan facility [Member]	Dec. 31, 2011 Revolving Credit Facility [Member]	Dec. 31, 2010 Revolving Credit Facility [Member]	Mar. 31, 2011 Cash flow hedge, interest rate swap [Member]	Dec. 31, 2010 Cash flow hedge, interest rate swap [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Initiation Date						December 21, 2011
Line of Credit Facility, Maximum Borrowing Capacity				$ 1,000.0
Line of Credit Facility, Amount Repaid					318.8
Line of Credit Facility, Amount Outstanding						560.0	0
Line of Credit Facility, Interest Rate Description				bears interest at varying rates based upon a base rate or LIBOR plus (in each case) a percentage based on the Company's debt rating with Standard & Poor's and Moody's Rating Services
Line of Credit Facility, Covenant Terms				The Credit Agreement also contains limitations on aggregate subsidiary indebtedness and a debt covenant that requires that the Company maintain on the last day of any period of four consecutive fiscal quarters, in each case taken as one accounting period, a ratio of total debt to consolidated EBITDA (Earnings Before Interest, Taxes, Depreciation, and Amortization) of not more than 3.0 to 1.0.
Line of Credit Facility, Covenant Compliance				The Company was in compliance with all covenants in the Credit Agreement at December 31, 2011.
Line of Credit Facility, Decrease, Repayments				235.0
Unamortized debt costs as interest expense					1.0
Line of Credit Facility, Interest Rate at Period End						1.26%
Interest Rate Swap Agreement [Abstract]
Fixed interest rate related to interest rate swap agreement		2.92%						2.92%
Interest rate swap agreement period	three-year
Variable interest rate related to interest rate swap agreement								three-month LIBOR rate
Interest rate swap liability		$ 0	$ 2.4						$ 2.4