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Employee Postretirement Benefits - Composition of Periodic Benefit Cost (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020
Retirement Benefits [Abstract] |  |  |
Net Periodic Benefit Cost | $ 5,913 | $ 11,366 | $ 12,617
Net Amount Amortized (Deferred) Due to the Effect of Regulation | 1,121 | 21 | (533)
Net Periodic Benefit Cost Recognized | $ 7,034 | $ 11,387 | $ 12,084

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