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Investments - Additional Information (Details) $ in Thousands | 6 Months Ended |
--- | --- | ---
Jun. 30, 2022 USD ($) security | Jun. 30, 2021 USD ($) | Dec. 31, 2021 USD ($)
Investment Holdings [Line Items] |  |  |
Accrued investment income | $ | $ 18,465 |  | $ 17,505
Fixed Income Securities |  |  |
Investment Holdings [Line Items] |  |  |
Accrued investment income | $ | $ 17,500 |  | 16,400
Number of debt securities for which there is an allowance for credit losses | security | 14 |  |
Number of debt securities in an unrealized loss position for which an allowance for credit losses has not been recorded | security | 1,341 |  |
Unrealized loss | $ | $ 202,650 |  | $ 16,891
Unrealized losses as percentage of fixed income portfolio cost basis | 8.20% |  |
Unrealized losses relative to total invested assets (as a percent) | 6.90% |  |
Number of unrealized loss positions | security | 1,341 |  |
Number of securities in unrealized loss positions for 12 months or longer | security | 133 |  |
Losses on fixed income securities | $ | $ 100 | $ 0 |

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