FINANCIAL INSTRUMENTS (Details ) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Carrying Value
Financial Instruments
Long-term debt	$ 742.5	$ 513.9
Carrying Value | Senior Credit Facility
Financial Instruments
Long-term debt	363.0	483.0
Carrying Value | Senior Notes
Financial Instruments
Long-term debt	349.4
Carrying Value | Series C Senior Note
Financial Instruments
Long-term debt	3.1	3.9
Carrying Value | Series D Senior Notes
Financial Instruments
Long-term debt	27.0	27.0
Fair Value
Financial Instruments
Long-term debt	763.4	513.9
Fair Value | Senior Credit Facility
Financial Instruments
Long-term debt	363.0	483.0
Fair Value | Senior Notes
Financial Instruments
Long-term debt	367.7
Fair Value | Series C Senior Note
Financial Instruments
Long-term debt	3.3	4.3
Fair Value | Series D Senior Notes
Financial Instruments
Long-term debt	$ 29.4	$ 26.6