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Investments (Net Investment Income) (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Statement [Line Items] |  |  |
Net investment income earned | $ 326,589 | $ 227,107 | $ 222,543
Fixed Income Securities [Member] |  |  |
Statement [Line Items] |  |  |
Net investment income earned | 209,709 | 203,926 | 203,255
Commercial Mortgage Loans [Member] |  |  |
Statement [Line Items] |  |  |
Net investment income earned | 2,743 | 844 | 0
Equity Securities [Member] |  |  |
Statement [Line Items] |  |  |
Net investment income earned | 15,920 | 9,286 | 6,996
Short-term Investments [Member] |  |  |
Statement [Line Items] |  |  |
Net investment income earned | 260 | 1,821 | 6,653
Other Investment Portfolio [Member] |  |  |
Statement [Line Items] |  |  |
Net investment income earned | 118,060 | 26,922 | 18,778
Investment Expenses [Member] |  |  |
Statement [Line Items] |  |  |
Net investment income earned | $ (20,103) | $ (15,692) | $ (13,139)

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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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