ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Summary of Changes by Component (Details) $ in Millions	9 Months Ended
	Sep. 30, 2019 USD ($)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance	$ 386.5
Other comprehensive loss before reclassifications	(30.8)
Amounts reclassified from AOCL	10.8
Net current-period other comprehensive loss before income tax	(20.0)
Income tax benefit	2.4
Other comprehensive loss	(17.6)
Ending Balance	406.1
Unrealized gains (losses) on Interest Rate Swaps
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance	(1.2)
Other comprehensive loss before reclassifications	(6.9)
Amounts reclassified from AOCL	0.5
Net current-period other comprehensive loss before income tax	(6.4)
Income tax benefit	1.7
Other comprehensive loss	(4.7)
Ending Balance	(5.9)
Foreign Currency Translation Adjustment
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance	(18.8)
Other comprehensive loss before reclassifications	(1.7)
Amounts reclassified from AOCL	0.0
Net current-period other comprehensive loss before income tax	(1.7)
Income tax benefit	0.0
Other comprehensive loss	(1.7)
Ending Balance	(20.5)
Foreign Currency Translation Adjustment on Long-term Intercompany Notes
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance	(8.1)
Other comprehensive loss before reclassifications	(9.2)
Amounts reclassified from AOCL	0.0
Net current-period other comprehensive loss before income tax	(9.2)
Income tax benefit	0.0
Other comprehensive loss	(9.2)
Ending Balance	(17.3)
Pension and Other Post-Employment Liability Adjustment
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance	(40.3)
Other comprehensive loss before reclassifications	(13.0)
Amounts reclassified from AOCL	10.3
Net current-period other comprehensive loss before income tax	(2.7)
Income tax benefit	0.7
Other comprehensive loss	(2.0)
Ending Balance	(42.3)
Total
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance	(68.4)
Ending Balance	$ (86.0)