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Employee Postretirement Benefits - Composition of Periodic Benefit Cost (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
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Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2025 | Sep. 30, 2024
Retirement Benefits [Abstract] |  |  |  |
Net Periodic Benefit Cost (Income) | $ (603) | $ (1,651) | $ (1,812) | $ (4,952)
Net Amount Amortized Due to the Effect of Regulation | 1,298 | 379 | 2,366 | 1,038
Net Periodic Benefit Cost (Income) Recognized | $ 695 | $ (1,272) | $ 554 | $ (3,914)

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