CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Parenthetical) - USD ($) $ in Millions	12 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Statement Of Stockholders Equity [Abstract]
Employee pension and postretirement benefits, tax	$ 19.4	$ 8.6	$ 14.9
Cash dividends declared per share on common stock (in dollars per share)	$ 1.32	$ 1.20	$ 1.08

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
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 45
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=123454820&loc=SL4569643-111683

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (c)(3)
-URI http://asc.fasb.org/extlink&oid=109239629&loc=SL4573702-111684

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