LONG-TERM OBLIGATIONS - Schedule of Fair Value (Details) $ in Millions	Dec. 31, 2018 USD ($) $ / shares	Dec. 31, 2017 USD ($) $ / shares
Senior Notes | 5-5/8% Notes
Debt Instrument [Line Items]
Book Value	$ 600.0	$ 600.0
FV	560.0	624.0
Credit Agreement | 2017 Credit Agreement Term Loan (net of discount)
Debt Instrument [Line Items]
Book Value	391.4	395.1
FV	$ 379.0	$ 398.0
Measurement Input, Quoted Price | Senior Notes | 5-5/8% Notes
Debt Instrument [Line Items]
Quote | $ / shares	0.93250	1.04000
Measurement Input, Quoted Price | Credit Agreement | 2017 Credit Agreement Term Loan (net of discount)
Debt Instrument [Line Items]
Quote | $ / shares	0.96750	1.00708