POSTRETIREMENT BENEFITS (Details 3) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Components of Net Periodic Benefit Cost [Abstract]
Service cost	$ 10.9	$ 11.3
Interest cost	75.1	94.7	$ 86.3
Amortization of prior service cost	(0.4)	0.0	0.1
Net periodic benefit cost	11.7	8.8	14.5
Included in Other Comprehensive Loss (Pretax)
Liability adjustment	(30.7)	177.7	100.6
Amortization of prior service costs and actuarial losses	46.3	29.1	37.0
Other Postretirement Benefit Plans, Defined Benefit
Components of Net Periodic Benefit Cost [Abstract]
Service cost	1.2	1.1	1.3
Interest cost	1.4	1.7	1.5
Amortization of prior service cost	0.1	0.0	0.0
Recognized actuarial loss	2.2	2.1	2.4
Net periodic benefit cost	(4.9)	(4.9)	(5.2)
Included in Other Comprehensive Loss (Pretax)
Liability adjustment	4.1	6.2	(2.1)
Amortization of prior service costs and actuarial losses	$ (2.3)	$ (2.1)	$ (2.4)