PENSION PLANS AND RETIREMENT BENEFITS (Details 2) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Pension Benefits
Service cost	$ 2.8	$ 2.8	$ 8.6	$ 8.5
Interest cost	12.8	18.8	38.4	56.3
Expected return on plans’ assets	(35.6)	(35.5)	(106.7)	(106.7)
Amortization of prior service cost	(0.1)	0.0	(0.4)	0.0
Recognized actuarial loss	13.2	11.2	39.5	33.5
Net periodic benefit (income) cost	(6.9)	(2.7)	(20.6)	(8.4)
Other Postretirement Benefits
Service cost	0.3	0.2	1.0	0.9
Interest cost	0.2	0.3	0.8	1.0
Expected return on plans’ assets	0.0	0.0	0.0	0.0
Amortization of prior service cost	0.0	0.0	0.1	0.0
Recognized actuarial loss	0.3	0.3	1.6	1.5
Net periodic benefit (income) cost	$ 0.8	$ 0.8	$ 3.5	$ 3.4