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Investments (Net Investment Income) (Details) - USD ($) $ in Thousands | 3 Months Ended
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Mar. 31, 2023 | Mar. 31, 2022
Net Investment Income [Line Items] |  |
Net investment income earned | $ 91,506 | $ 72,602
Fixed Income Securities [Member] |  |
Net Investment Income [Line Items] |  |
Net investment income earned | 80,087 | 53,925
Commercial Mortgage Loans [Member] |  |
Net Investment Income [Line Items] |  |
Net investment income earned | 1,965 | 970
Equity Securities [Member] |  |
Net Investment Income [Line Items] |  |
Net investment income earned | 1,205 | 2,418
Short-Term Investments [Member] |  |
Net Investment Income [Line Items] |  |
Net investment income earned | 4,650 | 101
Alternative Investments [Member] |  |
Net Investment Income [Line Items] |  |
Net investment income earned | 7,768 | 19,128
Other Investments [Member] |  |
Net Investment Income [Line Items] |  |
Net investment income earned | 43 | 177
Investment expenses [Member] |  |
Net Investment Income [Line Items] |  |
Net investment income earned | $ (4,212) | $ (4,117)

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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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