ACCUMULATED OTHER COMPREHENSIVE LOSS (Details) - USD ($)		3 Months Ended								6 Months Ended
		Jun. 30, 2022		Mar. 31, 2022		Jun. 30, 2021		Mar. 31, 2021		Jun. 30, 2022	Jun. 30, 2021
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		$ (2,078,600,000)		$ (2,014,100,000)		$ (1,958,700,000)		$ (1,862,000,000)		$ (2,014,100,000)	$ (1,862,000,000)
Foreign currency translation adjustment, net of tax		(3,000,000.0)				(500,000)				(2,000,000.0)	(5,400,000)
Amortization of pension related costs, net of tax	[1],[2]	2,800,000				3,500,000				5,700,000	7,000,000.0
Other comprehensive (loss) income, net		(200,000)	[3]	3,900,000	[3]	3,000,000.0	[3]	(1,400,000)	[3]	3,700,000	1,600,000
Ending balance		(2,348,200,000)		(2,078,600,000)		(2,020,000,000)		(1,958,700,000)		(2,348,200,000)	(2,020,000,000)
Foreign currency translation adjustment, tax expense										0	0
Amortization of pension related costs, tax expense		0				0				0	0
Accumulated Other Comprehensive (Loss) Income
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(230,800,000)		(234,700,000)		(279,300,000)		(277,900,000)		(234,700,000)	(277,900,000)
Other comprehensive (loss) income, net	[3]	(200,000)		3,900,000		3,000,000.0		(1,400,000)
Ending balance		(231,000,000.0)		(230,800,000)		$ (276,300,000)		$ (279,300,000)		(231,000,000.0)	$ (276,300,000)
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance				(25,800,000)						(25,800,000)
Foreign currency translation adjustment, net of tax										(2,000,000.0)
Other comprehensive (loss) income, net										(2,000,000.0)
Ending balance		(27,800,000)								(27,800,000)
Actuarial (Loss) Gain on Post-retirement Benefits
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance				(208,600,000)						(208,600,000)
Amortization of pension related costs, net of tax										5,700,000
Other comprehensive (loss) income, net										5,700,000
Ending balance		(202,900,000)								(202,900,000)
Other
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance				$ (300,000)						(300,000)
Other comprehensive (loss) income, net										0
Ending balance		$ (300,000)								$ (300,000)

[1] Net of tax expense of nil for both the three months ended and six months ended June 30, 2022 and 2021.

[2] This amount is included in the computation of net periodic benefit costs (income). See Note 10, "Pension and Post-Retirement Benefits," for additional information regarding net periodic benefit costs (income).

[3] See Note 13, "Accumulated Other Comprehensive Loss," regarding the changes in the accumulated balances for each component of other comprehensive loss during the six months ended June 30, 2022 and 2021, respectively.