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Commitments and Contingencies - Membership Interests of VIE Subject to Mandatory Redemption (Details) - USD ($) $ in Millions | Sep. 30, 2025 | Sep. 30, 2024
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Long-term Purchase Commitment [Line Items] |  |
Financial Instruments Subject to Mandatory Redemption, Settlement Terms, Share Value, Amount | $ 18 | $ 19
Minimum payments on membership interests subject to mandatory redemption, due in next twelve months | 1 |
Minimum payments on membership interests subject to mandatory redemption, due in year two | 1 |
Minimum payments on membership interests subject to mandatory redemption, due in year three | 1 |
Minimum payments on membership interests subject to mandatory redemption, due in year four | 2 |
Minimum payments on membership interests subject to mandatory redemption, due in year five | $ 2 |

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- Definition Minimum payments on membership interests subject to mandatory redemption, due in next twelve months + References No definition available. + Details
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- Definition Minimum payments on membership interests subject to mandatory redemption, due in year five + References No definition available. + Details
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- Definition Minimum payments on membership interests subject to mandatory redemption, due in year four + References No definition available. + Details
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- Definition Minimum payments on membership interests subject to mandatory redemption, due in year three + References No definition available. + Details
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- Definition 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. + Details
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- Definition Amount that would be paid, determined under the conditions specified in the contract, if the holder of the share has the right to redeem the shares. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 480 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 64 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481620/480-10-55-64 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 480 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481679/480-10-45-2 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 480 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481648/480-10-50-2 + Details
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