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Debt and Other Obligations Debt and Other Obligations - Lease/Leasebacks (Details) - USD ($) $ in Millions | 12 Months Ended | 348 Months Ended
--- | --- | ---
Sep. 30, 2053 | Sep. 30, 2023 | Sep. 30, 2052
Lagoon Creek [Member] |  |  |
Sale Leaseback Transaction [Line Items] |  |  |
Amortization of reacquired rights |  | $ 3 |
Lagoon Creek [Member] | Scenario, Forecast |  |  |
Sale Leaseback Transaction [Line Items] |  |  |
Amortization of reacquired rights | $ 2 |  | $ 5
Kemper/Lagoon Creek Leasehold Interests |  |  |
Sale Leaseback Transaction [Line Items] |  |  |
Leasehold Interests |  | 155 |
Lagoon Creek [Member] |  |  |
Sale Leaseback Transaction [Line Items] |  |  |
Leasehold Interests |  | 78 |
Kemper [Member] |  |  |
Sale Leaseback Transaction [Line Items] |  |  |
Leasehold Interests |  | $ 77 |

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- Definition Leasehold Interests + 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 Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 840 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481295/840-40-50-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479741/842-40-50-2 + Details
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