Summary of Significant Accounting Policies - Components of Other Current Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Sep. 30, 2023
Summary of Significant Accounting Policies [Line Items]
Prepayments	$ 18,463	$ 18,966
Prepaid Property and Other Taxes	14,187	14,186
Regulatory Assets	38,264	36,373
Other Current Assets	92,229	100,260
Federal
Summary of Significant Accounting Policies [Line Items]
Income Taxes Receivable	8,154	14,602
State
Summary of Significant Accounting Policies [Line Items]
Income Taxes Receivable	$ 13,161	$ 16,133

Summary Of Significant Accounting Policies [Line Items]

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Carrying amount as of the balance sheet date of income taxes previously overpaid to tax authorities (such as U.S. Federal, state and local tax authorities) representing refunds of overpayments or recoveries based on agreed-upon resolutions of disputes. Also called income tax refund receivable.

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Amount of current assets classified as other.

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Amount of asset related to consideration paid in advance for other costs that provide economic benefits within a future period of one year or the normal operating cycle, if longer.

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Amount of asset related to consideration paid in advance for income and other taxes that provide economic benefits within a future period of one year or the normal operating cycle, if longer.

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Carrying amount as of the balance sheet date of capitalized costs of regulated entities that are expected to be recovered through revenue sources within one year or the normal operating cycle, if longer. Such costs are capitalized if they meet both of the following criteria: a. It is probable that future revenue in an amount at least equal to the capitalized cost will result from inclusion of that cost in allowable costs for rate-making purposes. b. Based on available evidence, the future revenue will be provided to permit recovery of the previously incurred cost rather than to provide for expected levels of similar future costs. If the revenue will be provided through an automatic rate-adjustment clause, this criterion requires that the regulator's intent clearly be to permit recovery of the previously incurred cost.

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