Financial Instruments - Narrative (Details) |
3 Months Ended | 6 Months Ended | |||
|---|---|---|---|---|---|
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Mar. 31, 2026
USD ($)
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Mar. 31, 2025
USD ($)
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Mar. 31, 2026
USD ($)
MMcf
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Mar. 31, 2025
USD ($)
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Sep. 30, 2025
USD ($)
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| Derivative [Line Items] | |||||
| Purchase commitment volume | MMcf | 9,468 | ||||
| Contract netting | $ 0 | $ 0 | $ 0 | ||
| Cash collateral | 0 | 0 | $ 0 | ||
| Net (gain) loss on settled interest rate agreements | (6,100,000) | $ (5,100,000) | (12,300,000) | $ (10,200,000) | |
| Net realized gains in AOCI | $ 465,200,000 | $ 465,200,000 | |||
| Designated As Hedge | Gas Purchases | Commodity contracts | |||||
| Derivative [Line Items] | |||||
| Purchase commitment volume | MMcf | 23,800 | ||||
| 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% | |||
| X | ||||||||||
- Definition Accumulated Other Comprehensive Income (Loss), Derivatives Qualifying As Hedges Interest Rate Agreements, Realized Gain (Loss), Net of Tax No definition available.
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- Definition Fair value of liability associated with financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, and obligation to return cash collateral under master netting arrangements. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of right to receive cash collateral under master netting arrangements that have not been offset against derivative liabilities. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition The percentage of expected requirements covered by the aggregate notional amount of derivative contracts expressed in nonmonetary units. For example, the number of barrels specified in a fuel oil forward purchase contract as a percentage of expected need. No definition available.
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- Definition Nominal volume used to calculate payments on a derivative instrument. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition The amount of net gains or losses on interest rate cash flow hedges reclassified during the period to earnings from accumulated other comprehensive income upon the hedged transaction affecting earnings. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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