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Details of Selected Financial Statement Captions - Deferred Charges and Other Assets (Details) - USD ($) $ in Thousands | Sep. 30, 2025 | Sep. 30, 2024
--- | --- | ---
Balance Sheet Related Disclosures [Abstract] |  |
Marketable securities | $ 114,938 | $ 110,594
Regulatory assets (See Note 3) | 428,951 | 396,958
Operating lease right of use assets (See Note 7) | 293,934 | 249,556
Winter Storm Uri incremental costs | 0 | 6,424
Assets from risk management activities | 4,594 | 94,197
Pension and postretirement assets | 226,409 | 155,611
Other | 28,627 | 30,343
Total | $ 1,097,453 | $ 1,043,683

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