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v3.20.2

Summary of Significant Accounting Policies [Table Text Block] | 12 Months Ended
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Sep. 30, 2020
Accounting Policies [Abstract] |
Property, Plant, and Equipment Depreciation Rates | Average depreciation rates by asset class are as follows:
Property, Plant, and Equipment Depreciation Rates At September 30 (percent)
| 2020 |  | 2019 |  | 2018
Asset Class |  |  |  |  |
Nuclear | 2.38 |  |  | 2.38 |  |  | 2.64 |
Coal-fired(1) | 3.62 |  |  | 4.96 |  |  | 2.32 |
Hydroelectric | 1.60 |  |  | 1.61 |  |  | 1.57 |
Gas and oil-fired | 3.04 |  |  | 3.00 |  |  | 2.93 |
Transmission | 1.34 |  |  | 1.34 |  |  | 1.32 |
Other | 7.26 |  |  | 7.16 |  |  | 5.90 |

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