PENSION AND POST-RETIREMENT PLANS - COMPONENTS OF NET PERIODIC BENEFIT COST (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income, net of tax:
Amortization of net loss (gain)	$ (0.8)	$ (1.2)
Amortization of prior service credit	0.9	1.1
Pension Benefits
Components of Net Periodic Benefit Cost (Benefit):
Service cost	1.2	1.2
Interest cost	1.7	1.5
Expected return on plan assets	(3.9)	(3.6)
Amortization of net loss	0.8	1.3
Amortization of prior service credit	(0.3)	(0.6)
Net periodic benefit cost (benefit)	(0.5)	(0.2)
Post-retirement benefits
Components of Net Periodic Benefit Cost (Benefit):
Service cost	0.2	0.2
Interest cost	0.2	0.2
Amortization of net loss	0.2	0.3
Amortization of prior service credit	(0.9)	(0.9)
Net periodic benefit cost (benefit)	$ (0.3)	$ (0.2)