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Details of Selected Financial Statement Captions - Property, Plant and Equipment (Details) - USD ($) $ in Thousands | Sep. 30, 2025 | Sep. 30, 2024
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Balance Sheet Related Disclosures [Abstract] |  |
Storage plant | $ 790,621 | $ 708,617
Transmission plant | 6,308,557 | 5,713,831
Distribution plant | 19,788,099 | 17,304,207
General plant | 1,102,931 | 1,019,018
Intangible plant | 38,612 | 38,612
Property, plant and equipment | 28,028,820 | 24,784,285
Construction in progress | 1,235,316 | 1,063,798
Total property, plant and equipment and construction in progress | 29,264,136 | 25,848,083
Less: accumulated depreciation and amortization | (3,971,146) | (3,643,716)
Net property, plant and equipment | 25,292,990 | 22,204,367
Plant acquisition adjustments | $ (21,100) | $ (22,900)

X
- Definition Period end amount of total gross PPE excluding construction work in progress. + References No definition available. + Details
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X
- Definition Period end amount of property, plant and equipment (PPE) related to storage owned by public utility. + References No definition available. + Details
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- References No definition available. + Details
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- Definition Period end amount of construction work in progress in public utility. + References No definition available. + Details
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- Definition Period end amount of property, plant and equipment (PPE) related to utility distribution. + References No definition available. + Details
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- Definition Period end amount of total net PPE. + References No definition available. + Details
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- Definition Period end book value of other property, plant and equipment (PPE) owned (but not classified elsewhere) by the public utility. + References No definition available. + Details
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- Definition Period end amount of total gross PPE. + References No definition available. + Details
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