PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS - Components of Net Periodic Benefit Cost (Credit) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Pension
Components of Net Periodic Benefit Cost (Credit)
Service Cost	$ 1.7	$ 1.6	$ 3.3	$ 3.2
Interest Cost	9.6	10.1	19.3	20.2
Expected Return on Plan Assets	(11.2)	(11.0)	(22.4)	(21.9)
Amortization of Prior Service Credits	0.0	0.0	0.0	0.0
Amortization of Net Loss (Gain)	1.6	1.5	3.2	2.9
Net Periodic Benefit Cost (Credit)	1.7	2.2	3.4	4.4
Other Postretirement
Components of Net Periodic Benefit Cost (Credit)
Service Cost	0.4	0.5	0.8	1.1
Interest Cost	0.9	1.5	1.9	3.0
Expected Return on Plan Assets	(2.8)	(2.8)	(5.6)	(5.6)
Amortization of Prior Service Credits	(2.9)	(1.7)	(5.8)	(3.5)
Amortization of Net Loss (Gain)	(0.8)	(0.6)	(1.6)	(1.1)
Net Periodic Benefit Cost (Credit)	$ (5.2)	$ (3.1)	$ (10.3)	$ (6.1)