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Investments (Accrued Investment Income) (Details) - USD ($) $ in Thousands | Mar. 31, 2023 | Dec. 31, 2022
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Accrued Interest on Investments [Line Items] |  |
Accrued investment income | $ 57,340 | $ 59,167
Available-for-sale Securities [Member] |  |
Accrued Interest on Investments [Line Items] |  |
Accrued investment income | $ 55,900 | $ 56,400

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