ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Changes in accumulated other comprehensive income (loss) by component, net of taxes
Balance at the beginning of the period	$ 2,296.9	$ 1,667.4	$ 961.2
Other adjustments	1.2	0.2	(0.5)
Balance at the end of the period	2,400.7	2,296.9	1,667.4
Comprehensive Income (Loss):
Tax benefit (expense) on other comprehensive income (loss)	(1.2)	(9.3)	(8.1)
Pensions
Changes in accumulated other comprehensive income (loss) by component, net of taxes
Balance at the beginning of the period	(25.8)	(39.1)
Amortization of prior service cost		(0.8)
Amortization of net gain (loss)	5.5	14.1
Balance at the end of the period	(20.3)	(25.8)	(39.1)
Post Retirement
Changes in accumulated other comprehensive income (loss) by component, net of taxes
Balance at the beginning of the period	18.7	10.1
Amortization of prior service cost	(2.8)	(2.7)
Amortization of net gain (loss)	(4.9)	11.3
Balance at the end of the period	11.0	18.7	10.1
Non-Qualified Plans
Changes in accumulated other comprehensive income (loss) by component, net of taxes
Balance at the beginning of the period	0.1	(0.7)
Amortization of net gain (loss)	(0.3)	0.8
Balance at the end of the period	(0.2)	0.1	(0.7)
Other
Changes in accumulated other comprehensive income (loss) by component, net of taxes
Balance at the beginning of the period	0.1	(1.2)
Amortization of net gain (loss)		1.1
Foreign currency exchange	(0.5)	(0.4)
Other adjustments	1.7	0.6
Balance at the end of the period	1.3	0.1	(1.2)
Accumulated Other Comprehensive Income (Loss)
Changes in accumulated other comprehensive income (loss) by component, net of taxes
Balance at the beginning of the period	(6.9)	(30.9)	(50.8)
Amortization of prior service cost	(2.8)	(3.5)
Amortization of net gain (loss)	0.3	27.3
Foreign currency exchange	(0.5)	(0.4)
Other adjustments	1.7	0.6
Balance at the end of the period	$ (8.2)	$ (6.9)	$ (30.9)