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Investments - Additional Information (Detail) $ in Thousands | 3 Months Ended |
--- | --- | ---
Mar. 31, 2022 USD ($) Security | Mar. 31, 2021 USD ($) | Dec. 31, 2021 USD ($)
Marketable Securities [Line Items] |  |  |
Individual fixed maturity held in unrealized loss position | Security | 107 |  |
Individual fixed maturity held in unrealized loss position longer than 12 months | Security | 0 |  |
Number of fixed maturity securities, allowance for credit loss | Security | 362 |  |
Fixed maturity securities, allowance for credit loss | $ 290 |  | $ 195
Available-for-sale, Allowance for Credit Losses | 0 |  | 0
Net realized gains on investments | 738 | $ 319 |
Net unrealized gains on equity securities | 1,040 | $ 5,511 |
Corporate Bonds [Member] |  |  |
Marketable Securities [Line Items] |  |  |
Fixed maturity securities, allowance for credit loss | $ 241 |  | 143
Number of majority securities | Security | 26 |  |
States and Political Subdivisions [Member] |  |  |
Marketable Securities [Line Items] |  |  |
Fixed maturity securities, allowance for credit loss | $ 45 |  | $ 48
Number of majority securities | Security | 333 |  |
Corporate Fixed Income Securities [Member] | Maximum [Member] |  |  |
Marketable Securities [Line Items] |  |  |
Investments maturity period using default rate | 20 years |  |

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