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Plant Closures (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Sep. 30, 2022 | Sep. 30, 2021 | Sep. 30, 2020
Property, Plant and Equipment [Abstract] |  |  |
Accelerated depreciation | $ 140 | $ 136 | $ 125
Completed Plant |  |  |
Accelerated depreciation | 140 | 136 | 125
Property, Plant, and Equipment, Owned, Accumulated Depreciation | 482 |  |
Depreciation | 1,800 | $ 1,400 | $ 1,600
Additional depreciation for coal-fired fleet |  |  |
Completed Plant |  |  |
Depreciation | $ 339 |  |
Property, Plant and Equipment [Member] |  |  |
Completed Plant |  |  |
Property, Plant and Equipment, Dispositions | 22 million | 4 million | 13 million

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- Definition Describes an entity's accounting treatment for disposals of property, plant and equipment, including gains and losses related thereto. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section S99 -Paragraph 1 -URI https://asc.fasb.org/extlink&oid=27011434&loc=d3e125663-122742 + Details
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- Definition The cumulative amount of depreciation (related to long-lived, depreciable flight assets owned by the entity and used in the entity's principle business operations and capitalized assets classified as property, plant and equipment that are owned by the entity) that has been recognized in the income statement. + References No definition available. + Details
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