POSTRETIREMENT BENEFITS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Shareholders' Equity Charges
After-tax charge (benefit) to shareholders' equity for other postretirement plans	$ 4.7	$ 1.6
Pretax charge to shareholders' equity	177.7	100.6	$ 26.9
Other Postretirement Benefit Plans, Defined Benefit
Shareholders' Equity Charges
Pretax charge to shareholders' equity	6.2	$ (2.1)	$ 0.4
Par outstanding value of non-callable zero coupon bond used to determine the hypothetical yield curve	250.0
Defined Benefit Plan, Expected Future Benefit Payments in Year One	4.0
Defined Benefit Plan, Expected Future Benefit Payments in Year Two	4.0
Defined Benefit Plan, Expected Future Benefit Payments in Year Three	4.0
Defined Benefit Plan, Expected Future Benefit Payments in Year Four	4.0
Defined Benefit Plan, Expected Future Benefit Payments in Year Five	$ 4.0