Segment Information - Summary of Segment Information Reconciled to Consolidated Statements of Income (Parenthetical) (Detail) - USD ($) $ in Thousands |
3 Months Ended | |||||||
|---|---|---|---|---|---|---|---|---|
Mar. 31, 2025 |
Mar. 31, 2024 |
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| Segment Reporting Information [Line Items] | ||||||||
| Gross premiums earned | $ 300,383 | [1] | $ 256,644 | [2] | ||||
| Reciprocal Exchange Operation [Member] | ||||||||
| Segment Reporting Information [Line Items] | ||||||||
| Gross premiums earned | $ 1,199 | $ 453 | ||||||
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