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Investments (Estimated Fair Value Of Investments) (Details) - USD ($) $ in Thousands | 12 Months Ended |
--- | --- | ---
Dec. 31, 2020 | Dec. 31, 2019
Fixed maturity securities: |  |
Due in one year or less | $ 246,708 |
Due after one year through five years | 693,068 |
Due after five years through ten years | 540,052 |
Due after ten years | 2,069,982 |
Total | $ 3,549,810 | $ 3,093,275
External credit rating, non investment grade [Member] |  |
Credit Derivatives [Line Items] |  |
Percentage of fixed maturities | 1.30% |

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