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Schedule of Total Investment Return (Detail) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020
Investments, Debt and Equity Securities [Abstract] |  |  |
Net investment income | $ 27,627 | $ 37,020 | $ 28,392
Net realized investment gains (losses) | (32,929) | 15,887 | (14,662)
Change in unrealized holding gains (losses) | (61,627) | (34,363) | 21,779
Net realized and unrealized investment returns | (94,556) | (18,476) | 7,117
Total investment return | $ (66,929) | $ 18,544 | $ 35,509
Total investment return % | (4.70%) | 1.20% | 2.30%
Average investment portfolio | $ 1,437,327 | $ 1,490,933 | $ 1,528,425

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- Definition Amount, after investment expense, of income earned from investments in securities and real estate. Includes, but is not limited to, real estate investment, policy loans, dividends, and interest. Excludes realized gain (loss) on investments. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(2)) -URI https://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263 + Details
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