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v3.20.1

Revenue (Details) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Mar. 31, 2020 USD ($) percent | Mar. 31, 2019 USD ($) | Mar. 31, 2020 USD ($) percent | Mar. 31, 2019 USD ($)
State [Line Items] |  |  |  |
Electric revenue | $ (2,488) | $ (2,712) | $ (5,019) | $ (5,392)
Sales of Electricity | 2,489 | 2,712 | 5,021 | 5,393
Off System Sales of Electricity | 1 | 0 | 2 | 1
Other revenue | $ 32 | 38 | $ 78 | 82
Total long duration contract revenue recognition | 2,301 |  | 4,658 |
Total number of customers that represent a percent of sales | percent | 1 |  | 1 |
Revenues | $ 2,521 | $ 2,750 | $ 5,099 | $ 5,475
20-year Termination Notice [Member] |  |  |  |
State [Line Items] |  |  |  |
Number of customers that represent the percent of sales | percent | 1 |  | 1 |
Revenues | $ 1,737 |  | $ 3,506 |
10-year Termination Notice [Member] |  |  |  |
State [Line Items] |  |  |  |
Number of customers that represent the percent of sales | percent | 0 |  | 0 |
Revenues | $ 15 |  | $ 30 |
5-year termination notice [Member] |  |  |  |
State [Line Items] |  |  |  |
Number of customers that represent the percent of sales | percent | 0 |  | 0 |
Revenues | $ 549 |  | $ 1,122 |

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