PENSION AND POST-RETIREMENT PLANS - AMOUNTS INCLUDED IN FINANCIAL STATEMENTS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Employee benefit plans
Non-current assets	$ 49.0	$ 34.8
Non-current liabilities	(21.3)	(21.8)
Pension Benefits
Employee benefit plans
Projected benefit obligations	192.2	193.1	$ 187.4
Fair value of plan assets at end of year	241.2	227.9	206.3
Pension Benefits | Qualified Plan
Employee benefit plans
Non-current assets	49.0	34.8
Total	49.0	34.8
Net (loss) gain, net of taxes	(14.0)	(20.3)
Total	(14.0)	(20.3)
Pension Benefits | Nonqualified Plan
Employee benefit plans
Current liabilities	(0.4)	(1.2)
Non-current liabilities	(4.0)	(3.4)
Total	(4.4)	(4.6)
Net (loss) gain, net of taxes	(0.4)	(0.2)
Total	(0.4)	(0.2)
Post-retirement benefits
Employee benefit plans
Projected benefit obligations	$ 18.4	19.5	$ 15.3
Amortization period of unrecognized gains and losses	5 years
Post-retirement benefits | Qualified Plan
Employee benefit plans
Current liabilities	$ (1.1)	(1.1)
Non-current liabilities	(17.3)	(18.4)
Total	(18.4)	(19.5)
Net (loss) gain, net of taxes	2.5	2.7
Prior service credit, net of taxes	5.6	8.3
Total	$ 8.1	$ 11.0