ACCUMULATED OTHER COMPREHENSIVE LOSS (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		$ (2,014.1)	$ (1,862.0)
Foreign currency translation adjustment, net of tax		(1.8)	(8.7)
Amortization of pension related costs, net of tax	[1],[2]	11.5	13.8
Pension re-measurement, net of tax	[3]	5.6	38.1
Settlement and curtailment gain, net of tax	[1]	(0.5)	0.0
Other comprehensive (loss) income, net	[4]	14.8	43.2
Ending balance		(2,662.7)	(2,014.1)
Pension re-measurement, tax expense		0.3	0.3
Foreign currency translation adjustment, tax expense		0.0	0.0
Amortization of pension related costs, tax expense		0.0	0.0
Pension settlement and curtailment, tax expense		0.0	0.0
Accumulated Other Comprehensive (Loss) Income
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(234.7)	(277.9)
Other comprehensive (loss) income, net	[4]	14.8	43.2
Ending balance		(219.9)	(234.7)
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(25.8)	(17.1)
Foreign currency translation adjustment, net of tax		(1.8)	(8.7)
Other comprehensive (loss) income, net		(1.8)	(8.7)
Ending balance		(27.6)	(25.8)
Actuarial (Loss) Gain on Post-retirement Benefits
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(208.6)	(260.5)
Amortization of pension related costs, net of tax		11.5	13.8
Pension re-measurement, net of tax		5.6	38.1
Settlement and curtailment gain, net of tax		(0.5)
Other comprehensive (loss) income, net		16.6	51.9
Ending balance		(192.0)	(208.6)
Pension re-measurement, tax expense		0.3	0.3
Other
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(0.3)	(0.3)
Other comprehensive (loss) income, net		0.0	0.0
Ending balance		$ (0.3)	$ (0.3)

[1] Net of tax expense of nil for the years ended December 31, 2022 and 2021.

[2] This amount is included in the computation of net periodic benefit costs (income). See Note 11, "Pension and Post-Retirement Benefits," for additional information regarding net periodic benefit costs (income).

[3] Net of tax expense of $0.3 million for each of the years ended December 31, 2022 and 2021.

[4] See Note 14, "Accumulated Other Comprehensive Loss," regarding the changes in the accumulated balances for each component of other comprehensive loss during the years ended December 31, 2022 and 2021, respectively.