Earnings Per Share - Weighted Average Common Shares Used in Computations of Basic and Diluted Earnings per Share (Detail) - shares shares in Thousands	3 Months Ended	6 Months Ended
Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021
Earnings Per Share [Abstract]
Average common shares outstanding (shares)	285,243	291,095	284,961	290,839
Dilutive share equivalents from share-based plans (shares)	2,003	2,452	2,215	2,660
Dilutive share equivalents from Series C preferred shares (shares)	53	0	26	0
Average common and common equivalent shares outstanding - assuming dilution (shares)	287,299	293,547	287,202	293,499
Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Share equivalents excluded from the diluted shares outstanding calculation (shares)	5,639	6,169	5,639	6,169
Share Based Compensation
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Share equivalents excluded from the diluted shares outstanding calculation (shares)	0	773	676	773

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of convertible preferred stock using the if-converted method.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=124432515&loc=d3e3550-109257

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=125511455&loc=d3e2029-109256

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 40
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=125511455&loc=d3e1930-109256

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The sum of dilutive potential common shares or units used in the calculation of the diluted per-share or per-unit computation.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=124432515&loc=d3e3550-109257

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The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

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