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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 |

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- Definition 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. + References 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 + Details
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