Benefit Plans - Pension Plans with Accumulated Benefit Obligations (Detail) - USD ($) $ in Millions	Sep. 30, 2022	Sep. 30, 2021
Retirement Benefits [Abstract]
Accumulated benefit obligation exceeds the fair value of plan assets, projected benefit obligation	$ 2,104	$ 3,406
Projected benefit obligation exceeds the fair value of plan assets, projected benefit obligation	2,182	3,475
Accumulated benefit obligation exceeds the fair value of plan assets, accumulated benefit obligation	2,059	3,309
Accumulated benefit obligation exceeds the fair value of plan assets, fair value of plan assets	1,644	2,712
Projected benefit obligation exceeds the fair value of plan assets, fair value of plan assets	$ 1,720	$ 2,780

No definition available.

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Amount of plan asset for defined benefit pension plan with projected benefit obligation in excess of plan assets.

+ References

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- Definition

Amount of projected benefit obligation for defined benefit pension plan with projected benefit obligation in excess of plan assets.

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- Definition

Amount of accumulated benefit obligation for defined benefit plan with accumulated benefit obligation in excess of plan assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
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Amount of plan asset for defined benefit plan with accumulated benefit obligation in excess of plan assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 3
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Amount of projected benefit obligation for defined benefit pension plan with accumulated benefit obligation in excess of plan assets.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=123447040&loc=d3e2417-114920

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