PENSION AND POST-RETIREMENT PLANS - AMOUNTS INCLUDED IN FINANCIAL STATEMENTS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Employee benefit plans
Non-current assets	$ 18.9	$ 1.3
Non-current liabilities	(17.8)	(43.3)
Pension Benefits
Employee benefit plans
Projected benefit obligations	187.4	249.5	$ 263.1
Fair value of plan assets at end of year	206.3	238.9	212.8
Pension Benefits | Qualified Plan
Employee benefit plans
Non-current assets	18.9	1.3
Non-current liabilities		(11.9)
Total	18.9	(10.6)
Net (loss) gain, net of taxes	(25.8)	(39.9)
Prior service credit, net of taxes		0.8
Total	(25.8)	(39.1)
Projected benefit obligations		247.8
Accumulated benefit obligation		247.4
Fair value of plan assets at end of year		235.8
Pension Benefits | Nonqualified Plan
Employee benefit plans
Current liabilities	(0.7)	(1.8)
Non-current liabilities	(3.4)	(3.0)
Total	4.1	4.8
Net (loss) gain, net of taxes	0.1	(0.7)
Total	0.1	(0.7)
Post-retirement benefits
Employee benefit plans
Projected benefit obligations	$ 15.3	29.3	$ 29.1
Amortization period of unrecognized gains and losses	5 years
Post-retirement benefits | Qualified Plan
Employee benefit plans
Current liabilities	$ (0.9)	(0.9)
Non-current liabilities	(14.4)	(28.4)
Total	(15.3)	(29.3)
Net (loss) gain, net of taxes	7.6	(3.7)
Prior service credit, net of taxes	11.1	13.9
Total	$ 18.7	$ 10.2