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v3.25.1

Financial Instruments - Narrative (Details) | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Mar. 31, 2025 USD ($) | Mar. 31, 2024 USD ($) | Mar. 31, 2025 USD ($) MMcf | Mar. 31, 2024 USD ($) | Sep. 30, 2024 USD ($)
Derivative [Line Items] |  |  |  |  |
Purchase commitment volume | MMcf |  |  | 4,017 |  |
Contract netting | $ 0 |  | $ 0 |  | $ 0
Cash collateral | 0 |  | 0 |  | $ 0
Net (gain) loss on settled interest rate agreements | (5,100,000) | $ (3,200,000) | (10,200,000) | $ (6,400,000) |
Net realized gains in AOCI | $ 387,000,000.0 |  | $ 387,000,000.0 |  |
Designated As Hedge | Gas Purchases | Commodity contracts |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Purchase commitment volume | MMcf |  |  | 24,000.0 |  |
Designated As Hedge | Gas Purchases | Commodity contracts | Minimum |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Hedging percent | 25.00% |  | 25.00% |  |
Designated As Hedge | Gas Purchases | Commodity contracts | Maximum |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Hedging percent | 50.00% |  | 50.00% |  |

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