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Net Investment Income (Net Investment Income) (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020
Net Investment Income [Line Items] |  |  |
Gross investment income | $ 789,106 | $ 679,414 | $ 592,946
Investment expense | (9,921) | (7,796) | (9,125)
Net investment income | 779,185 | 671,618 | 583,821
Fixed maturity securities, including cash and cash equivalents and loans receivable |  |  |
Net Investment Income [Line Items] |  |  |
Gross investment income | 549,281 | 382,001 | 426,563
Investment funds |  |  |
Net Investment Income [Line Items] |  |  |
Gross investment income | 145,099 | 220,014 | 54,253
Arbitrage trading account |  |  |
Net Investment Income [Line Items] |  |  |
Gross investment income | 45,213 | 37,676 | 77,931
Real estate |  |  |
Net Investment Income [Line Items] |  |  |
Gross investment income | (3,087) | 7,703 | 24,027
Equity securities |  |  |
Net Investment Income [Line Items] |  |  |
Gross investment income | $ 52,600 | $ 32,020 | $ 10,172

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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 http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263 + Details
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