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Asset Retirement Obligations Asset Retirement Obligations (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Sep. 30, 2020 | Sep. 30, 2019 | Sep. 30, 2018
Liabilities Settled [Line Items] |  |  |  |
Increase in ARO liability |  | $ 1,200 |  |
Change in estimate | [1] | 1,077 | $ 50 |
Costs for asbestos |  |  | 114 |
Allen West ARO increase |  | 273 | 33 |
Paradise ARO increase (decrease) |  |  | 57 |
Allen East ARO increase (decrease) |  |  | 44 |
Gallatin CCR ARO increase (decrease) |  | 173 | 672 |
Additional obligations | [1] |  | 18 |
Gallatin CCR |  |  | 672 |
Balance | [1] | 6,785 | 5,616 | $ 4,779
Asset Retirement Obligation, Liabilities Settled | [1] | 114 | 89 |
Accretion (recorded as regulatory asset) | [1] | 206 | 186 |
Asset Retirement Obligation, Current |  | 345 | 163 |
Amortization and Depreciation of Decontaminating and Decommissioning Assets |  | 169 | 144 | 144
Total ARO change due to CCR |  | 129 |  |
Change in ARO from operating CCR facilities |  | 38 |  |
Change in ARO from inactive CCR facilities |  | 91 |  |
Increase in CCR post-closure care |  | 460 |  |
Change in plant decommissioning obligations |  | 19 |  |
Accounts payable and accrued liabilities |  |  |  |
Liabilities Settled [Line Items] |  |  |  |
Asset Retirement Obligation, Current |  | 345 | 163 |
Nuclear |  |  |  |
Liabilities Settled [Line Items] |  |  |  |
Revision of estimate (other non nuclear) |  | 0 | (250) |
Change in estimate |  |  | 0 |
Additional obligations |  |  | 18 |
Gallatin CCR |  |  | 0 |
Balance |  | 3,278 | 3,136 | 2,989
Asset Retirement Obligation, Liabilities Settled |  | 1 | 7 |
Accretion (recorded as regulatory asset) |  | 143 | 136 |
Non-nuclear |  |  |  |
Liabilities Settled [Line Items] |  |  |  |
Change in estimate |  | 1,077 | 50 |
Additional obligations |  |  | 0 |
Gallatin CCR |  |  | 672 |
Balance |  | 3,507 | 2,480 | $ 1,790
Asset Retirement Obligation, Liabilities Settled |  | 113 | 82 |
Accretion (recorded as regulatory asset) |  | $ 63 | $ 50 |
[1] | (1) Includes $345 million a nd $163 million at September 30, 2020 and 2019, respectively, in Current liabilities.

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