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Investments - Additional Information (Detail) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2024 USD ($) Security | Dec. 31, 2023 USD ($)
Marketable Securities [Line Items] |  |
Short-term investments |  | $ 0
Individual fixed maturity held in unrealized loss position | Security | 187 |
Individual fixed maturity held in unrealized loss position longer than 12 months | Security | 40 |
Number of fixed maturity securities, allowance for credit loss | Security | 416 |
Fixed maturity securities, held-to-maturity, allowance for credit losses | $ 116,000 | 182,000
Fixed maturity securities, available-for-sale, allowance for credit losses | 0 | 0
Held-to-Maturity Securities [Member] |  |
Marketable Securities [Line Items] |  |
Investments on deposit with regulatory agencies | 22,600,000 |
Available-for-Sale Securities [Member] |  |
Marketable Securities [Line Items] |  |
Investments on deposit with regulatory agencies | 2,100,000 |
Corporate Bonds [Member] |  |
Marketable Securities [Line Items] |  |
Short-term investments | 9,300,000 |
Fixed maturity securities, held-to-maturity, allowance for credit losses | $ 86,000 | 142,000
Number of majority securities | Security | 15 |
States and Political Subdivisions [Member] |  |
Marketable Securities [Line Items] |  |
Fixed maturity securities, held-to-maturity, allowance for credit losses | $ 30,000 | $ 38,000
Number of majority securities | Security | 398 |
Corporate Fixed Income Securities [Member] | Maximum [Member] |  |
Marketable Securities [Line Items] |  |
Investments maturity period using default rate | 20 years |

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