ACCRUED LIABILITIES (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Accrued Liabilities, Current [Abstract]
Accrued compensation and payroll taxes	$ 82.5	$ 77.8
Tax-related accruals	34.4	40.9
Accrued interest	37.4	30.7
Legal and professional costs	31.8	21.2
Accrued employee benefits	21.7	21.2
Environmental (current portion only)	20.0	17.0
Asset retirement obligation (current portion only)	10.5	12.6
Other	36.1	42.4
Accrued liabilities	$ 274.4	$ 263.8