CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Parenthetical) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Dec. 31, 2021	Dec. 31, 2023	Dec. 31, 2022	Sep. 30, 2021
Statement of Stockholders' Equity [Abstract]
Employee pension and postretirement benefits, tax	$ 2.6	$ 0.9	$ 17.3	$ 19.4
Cash dividends declared per share on common stock (in dollars per share)	$ 0.37	$ 1.64	$ 1.48	$ 1.32

Amount, after reclassification adjustment, of tax (expense) benefit for (increase) decrease in accumulated other comprehensive income for defined benefit plan, attributable to parent.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 810
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 19
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481231/810-10-45-19

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 45
-Paragraph 20
-SubTopic 10
-Topic 810
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481231/810-10-45-20

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 1A
-Subparagraph (c)(3)
-SubTopic 10
-Topic 810
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481203/810-10-50-1A

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Balance Type:	credit
Period Type:	duration