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Investments - A Summary of the Company's Realized Gains and Losses on Sales, Calls or Redemptions of Investments (Detail) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020
Marketable Securities [Line Items] |  |  |
Proceeds from sales | $ 50,992 | $ 40,579 | $ 72,395
Gross realized investment gains | 3,715 | 1,754 | 1,017
Gross realized investment (losses) | (51) | (21) | (18)
Net realized investment gains (losses) | 3,664 | 1,733 | 999
Other, including gains (losses) on calls and redemptions | (224) | (38) | 133
Net realized gains (losses) on investments | 3,440 | 1,695 | 1,132
Fixed Maturity Securities Available for Sale [Member] |  |  |
Marketable Securities [Line Items] |  |  |
Proceeds from sales | 42,505 | 28,191 | 25,436
Gross realized investment gains | 365 | 1,751 | 711
Gross realized investment (losses) | (51) | (21) | (14)
Net realized investment gains (losses) | 314 | 1,730 | 697
Other, including gains (losses) on calls and redemptions | (200) | (6) | (43)
Net realized gains (losses) on investments | 114 | 1,724 | 654
Equity Securities [Member] |  |  |
Marketable Securities [Line Items] |  |  |
Proceeds from sales | 8,487 |  |
Gross realized investment gains | 3,350 |  |
Net realized investment gains (losses) | 3,350 |  |
Net realized gains (losses) on investments | 3,350 |  |
Other [Member] |  |  |
Marketable Securities [Line Items] |  |  |
Proceeds from sales |  | 12,388 | 46,959
Gross realized investment gains |  | 3 | 306
Gross realized investment (losses) |  |  | (4)
Net realized investment gains (losses) |  | 3 | 302
Other, including gains (losses) on calls and redemptions | (24) | (32) | 176
Net realized gains (losses) on investments | $ (24) | $ (29) | $ 478

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