ACCUMULATED OTHER COMPREHENSIVE LOSS - Components of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018		Mar. 31, 2017
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		$ (770.4)
Other comprehensive income		0.2	[1]	$ 9.9
Ending balance		(855.7)
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(228.4)
Other comprehensive income	[1]	0.2
Ending balance		(228.2)
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(15.0)
Other comprehensive income		(2.5)
Ending balance		(17.5)
Actuarial (Loss) Gain on Post-retirement Benefits
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(212.4)
Other comprehensive income		2.1
Ending balance		(210.3)
Actuarial (Loss) Gain on Post-retirement Benefits - Amortization of pension related costs
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Other comprehensive income		2.1
Other comprehensive income (loss), tax benefit (expense)		(0.3)
Deferred Gain (Loss) - Hedging
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(0.7)
Other comprehensive income		0.6
Ending balance		(0.1)
Deferred Gain (Loss) - Hedging - amortization of deferred gains (losses) related to the de-designated 2013 Interest Rate Swap
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Other comprehensive income		0.6
Other comprehensive income (loss), tax benefit (expense)		0.2
Other
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(0.3)
Other comprehensive income		0.0
Ending balance		$ (0.3)

[1] See Note 12, "Accumulated Other Comprehensive Loss," regarding the changes in the accumulated balances for each component of other comprehensive loss during the three months ended March 31, 2018.