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Components of Net Realized Investment Gains (Losses) (Detail) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020
Schedule Of Available For Sale Securities [Line Items] |  |  |
Total net realized investment gains (losses) | $ (32,929) | $ 15,887 | $ (14,662)
Equity securities, Gross realized gains | 2,289 | 15,350 | 16,997
Equity securities, Gross realized losses | (5,681) | (1,910) | (32,247)
Equity securities, Total net realized investment gains (losses) | (3,392) | 13,440 | (15,250)
Not Designated as Hedging Instrument | Interest Rate Swap |  |  |
Schedule Of Available For Sale Securities [Line Items] |  |  |
Gross realized gains | 12,844 | 8,035 | 19,460
Gross realized losses | (2,771) | (5,930) | (41,716)
Total net realized investment gains (losses) | 10,073 | 2,105 | (22,256)
Fixed Income Securities |  |  |
Schedule Of Available For Sale Securities [Line Items] |  |  |
Gross realized gains | 688 | 11,390 | 28,381
Gross realized losses | (40,298) | (11,048) | (5,537)
Total net realized investment gains (losses) | $ (39,610) | $ 342 | $ 22,844

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- Definition Amount of unrealized and realized gain (loss) on investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 321 -SubTopic 10 -Section 50 -Paragraph 4 -URI https://asc.fasb.org/extlink&oid=126980263&loc=SL75117546-209714 + Details
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