Fair Value Measurements - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Impairment of Assets	$ 519,129	$ 0	$ 0
Northern Access Project
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Impairment of Assets	$ 46,100

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/2003/role/exampleRef
-Topic 820
-SubTopic 10
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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