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POSTRETIREMENT BENEFITS (Details) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
Shareholders' Equity Charges |  |  |
Pretax benefit (charge) to shareholders' equity | $ 16.4 | $ (59.9) | $ (245.9)
Other Postretirement Benefit Plans, Defined Benefit |  |  |
Shareholders' Equity Charges |  |  |
After-tax benefit (charge) to shareholders' equity for other postretirement plans | 1.3 | (9.6) |
Pretax benefit (charge) to shareholders' equity | 1.7 | $ (12.2) | $ (3.8)
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 | 3.0 |  |
Defined Benefit Plan, Expected Future Benefit Payments in Year Two | 3.0 |  |
Defined Benefit Plan, Expected Future Benefit Payments in Year Three | 3.0 |  |
Defined Benefit Plan, Expected Future Benefit Payments in Year Four | 2.0 |  |
Defined Benefit Plan, Expected Future Benefit Payments in Year Five | $ 2.0 |  |

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- Definition Aftertax change in the value of either the benefit obligation or the plan assets resulting from experience different from that assumed or from a change in an actuarial assumption, or the consequence of a decision to temporarily deviate from the substantive plan, that has not been recognized in net periodic benefit cost. + References No definition available. + Details
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- Definition Amount of benefit for defined benefit plan expected to be paid in next fiscal year following current fiscal year. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (f) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + Details
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- Definition Amount of benefit for defined benefit plan expected to be paid in fifth fiscal year following current fiscal year. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (f) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + Details
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