PENSION PLANS (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 2.4	$ 14.9
After-tax benefit (charge) to shareholders' equity	(17.9)	145.5
Pretax benefit (charge) to shareholders' equity	$ (30.7)	$ 177.7	$ 100.6
Basis point increase (decrease) in the plans' discount rate reflected in benefit (charge) to shareholders' equity	(80)	(100)
Actuarial loss	$ 235.1	$ 364.1
Benefit obligation	3,205.3	2,997.8	2,667.8
Projected benefit payments [Abstract]
Par outstanding value of bonds used to determine the discount rate yield curve	$ 250.0
Historic rate of return on plan assets in the last 5 year period	11.70%
Historic rate of return on plan assets in the last 10 year period	9.60%
Historic rate of return on plan assets in the last 15 year period	10.10%
Qualified plans
Projected benefit payments [Abstract]
2021	$ 146.6
2022	147.0
2023	147.8
2024	148.7
2025	149.0
Non-qualified plans
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation	5.9	5.8
Projected benefit payments [Abstract]
2021	0.8
2022	0.4
2023	0.4
2024	0.4
2025	0.3
U.S. | Qualified plans
Defined Benefit Plan Disclosure [Line Items]
Employer contributions		12.5
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	0.0
Foreign | Qualified plans
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	2.1	$ 2.4	$ 2.6
Foreign | Qualified plans | Maximum
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	$ 5.0