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Contingencies and Legal Proceedings Legal Proceedings (Details) | 6 Months Ended
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Mar. 31, 2021 USD ($) Groups Agreements Units
Legal Proceedings |
Number of licensed nuclear units | Units | 7
Legal loss contingency accrual | $ 12,000,000
Amount remaining to be spent under environmental agreements [Abstract] | 11,000,000
General |
Legal Proceedings |
Legal loss contingency accrual | $ 14,000,000
Environmental Agreements |
Legal Proceedings |
Number of similar environmental agreements entered into | Agreements | 2
Number of environmental agreements entered into with the EPA | Agreements | 1
Number of environmental agreements entered into with environmental advocacy groups | Groups | 3
Amount to be invested in certain TVA environmental projects | $ 290,000,000
Accounts payable and accrued liabilities | General |
Legal Proceedings |
Legal loss contingency accrual | $ 30,000,000

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