For a classified balance sheet, the carrying amount as of the balance sheet date of the portion of the obligations recognized for the various benefits provided to former or inactive employees, their beneficiaries, and covered dependents after employment but before retirement that is payable within one year of the balance sheet date.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(20))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 712
-SubTopic 10
-Name Accounting Standards Codification
-Section 25
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481179/712-10-25-4

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 712
-SubTopic 10
-Name Accounting Standards Codification
-Section 25
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481179/712-10-25-5

Name:	us-gaap_PostemploymentBenefitsLiabilityCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Benefit Plans Other Postemployment Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2026
Other Post-Employment Benefits
Discount rate	4.16%	3.81%	4.59%
Period expense	$ 3	$ 21	$ 3
Postemployment benefits liability, noncurrent	233	258
Accounts Payable and Accrued Liabilities
Other Post-Employment Benefits
Postemployment Benefits Liability, Current	25	28
Accounts Payable and Accrued Liabilities \| Scenario, Forecast
Other Post-Employment Benefits
Postemployment Benefits Liability, Current				$ 24
Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent
Other Post-Employment Benefits
Postemployment benefits liability, noncurrent	$ 208	$ 230	$ 266