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Risk Management Activities and Derivative Transactions Risk Management Activities and Derivative Transactions - Other Derivative Instruments (Details) - USD ($) $ in Millions | Sep. 30, 2025 | Sep. 30, 2024
--- | --- | ---
Derivative |  |
Forward Contract Derivative Asset, at Fair Value | $ 16 | $ 11
Derivative Liability, Subject to Master Netting Arrangement, after Offset | 884 | 1,122
Fair Value, Inputs, Level 2 |  |
Derivative |  |
Forward Contract Derivative Asset, at Fair Value | $ 16 | $ 11

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