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Investments - Maturities of Fixed Maturities (Details) - USD ($) $ in Thousands | 12 Months Ended |
--- | --- | ---
Dec. 31, 2020 | Dec. 31, 2019
Amortized Cost |  |
Due in 1 year or less | $ 255,416 |
Due after 1 year through 5 years | 1,712,114 |
Due after 5 years through 10 years | 1,608,614 |
Due after 10 years through 20 years | 1,358,865 |
Due after 20 years | 853,542 |
Amortized Cost | 5,788,551 | $ 5,456,980
Fair Value |  |
Due in 1 year or less | 261,387 |
Due after 1 year through 5 years | 1,793,111 |
Due after 5 years through 10 years | 1,775,766 |
Due after 10 years through 20 years | 1,559,501 |
Due after 20 years | 955,525 |
Total | $ 6,345,290 | $ 5,791,676
Percent of Total Fair Value |  |
Due in 1 year or less | 4.00% |
Due after 1 year through 5 years | 28.30% |
Due after 5 years through 10 years | 28.00% |
Due after 10 years through 20 years | 24.60% |
Due after 20 years | 15.10% |
Total | 100.00% |
Average option-adjusted duration, in years | 6 years 4 months 24 days |

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