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v3.21.2

Risk Management Activities and Derivative Transactions Risk Management Activities and Derivative Transactions - Counterparty Credit Risk (Details) $ in Millions | 12 Months Ended |
--- | --- | ---
Sep. 30, 2021 USD ($) megawatts Customers | Sep. 30, 2020 USD ($)
Derivative |  |
Receivables from power sales | $ | $ 1,480 | $ 1,401
Credit of Customers |  |
Derivative |  |
Number of customers that represent the percent of sales | Customers | 2 |
Long-term Contract for Purchase of Electric Power [Domain] |  |
Derivative |  |
Megawatts | megawatts | 440 |

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- Definition Amount, before allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as current. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=124259787&loc=d3e4428-111522 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 9 -URI http://asc.fasb.org/extlink&oid=124259787&loc=d3e4531-111522 + Details
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