LONG-TERM DEBT AND NOTES PAYABLE - Long-term Debt Outstanding (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Total debt	$ 265.8	$ 299.9
Less: current portion	(16.0)	(50.0)
Long-term debt (less current portion)	249.8	249.9
5.368% Notes, due December 1, 2015
Debt Instrument [Line Items]
Total debt	80.0	80.0
Debt instrument, interest rate, stated percentage	5.368%	5.368%
5.20% Notes, due January 15, 2020
Debt Instrument [Line Items]
Total debt	40.0	40.0
Debt instrument, interest rate, stated percentage	5.20%	5.20%
3.86% Notes, due December 21, 2021
Debt Instrument [Line Items]
Total debt	50.0	50.0
Debt instrument, interest rate, stated percentage	3.86%	3.86%
5.70% Notes, due January 15, 2035
Debt Instrument [Line Items]
Total debt	34.8	34.9
Debt instrument, interest rate, stated percentage	5.70%	5.70%
5.90% Notes, due January 15, 2037
Debt Instrument [Line Items]
Total debt	45.0	45.0
Debt instrument, interest rate, stated percentage	5.90%	5.90%
Revolving credit facility
Debt Instrument [Line Items]
Total debt	$ 16.0	$ 50.0