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Risk Management Activities and Derivative Transactions Derivatives Under FTP (Details) - USD ($) $ in Millions | Jun. 30, 2023 | Sep. 30, 2022
--- | --- | ---
Derivative |  |
Forward Contract Derivative Asset, at Fair Value | $ 8 | $ 4
Fair value | 78 | 1
Natural Gas Contract Derivatives |  |
Derivative |  |
Fair value | 18 | 145
Commodity Contract under FHP |  |
Derivative |  |
Fair value | (247) | 115
Fair Value, Inputs, Level 2 |  |
Derivative |  |
Forward Contract Derivative Asset, at Fair Value | $ 8 | $ 4

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