PENSION AND POST-RETIREMENT PLANS - COMPONENTS OF NET PERIODIC BENEFIT COST (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Pension Benefits
Components of net periodic benefit cost (credit):
Service cost	$ 1.3	$ 1.1	$ 3.5	$ 2.8
Interest cost	2.6	2.4	7.8	7.3
Expected return on plan assets	(4.4)	(3.8)	(13.2)	(11.4)
Amortization of net actuarial loss (gain)		0.1		0.3
Net periodic benefit credit	(0.5)	(0.2)	(1.9)	(1.0)
Post-retirement benefits
Components of net periodic benefit cost (credit):
Service cost			0.1	0.2
Interest cost	0.3	0.3	0.8	0.8
Amortization of net actuarial loss (gain)	(0.2)	(0.2)	(0.5)	(0.6)
Amortization of prior service credit	(2.7)	(1.0)	(4.6)	(2.8)
Net periodic benefit credit	$ (2.6)	$ (0.9)	$ (4.2)	$ (2.4)