PENSION AND POST-RETIREMENT BENEFITS - Classification of Net Periodic Pension (Income) Costs (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total net periodic benefit costs	$ 1.3	$ 1.2	$ 4.0
Selling, general and administrative expense
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total net periodic benefit costs	0.4	0.4
Miscellaneous, net
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total net periodic benefit costs	$ 0.9	$ 0.8