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Investments (Summary Of Net Investment Gains (Losses) And The Change In Net Unrealized Gains On Investments) (Details) - USD ($) $ in Thousands | 3 Months Ended
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Mar. 31, 2024 | Mar. 31, 2023
Gain (Loss) on Securities [Line Items] |  |
Debt Securities, Available-for-Sale, Realized Gain (Loss) | $ (4,488) | $ (3,221)
Equity securities, Change in fair value of securities sold during the period | 43 | 5,637
Equity securities, Change in fair value of securities held at the end of the period | 906,726 | 370,147
Total change in fair value of equity securities | 906,769 | 375,784
Net investment gains (losses) | 902,281 | 372,563
Change in net unrealized losses on available-for-sale investments included in other comprehensive income (loss): | (155,769) | 208,369
Fixed Maturities [Member] |  |
Gain (Loss) on Securities [Line Items] |  |
Change in net unrealized losses on available-for-sale investments included in other comprehensive income (loss): | (148,487) | 209,179
Short-term investments [Member] |  |
Gain (Loss) on Securities [Line Items] |  |
Change in net unrealized losses on available-for-sale investments included in other comprehensive income (loss): | $ (7,282) | $ (810)

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- Definition Amount of realized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 9 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-9 + Details
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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/2003/role/disclosureRef -Topic 944 -SubTopic 220 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(3)(d)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147483586/944-220-S99-1 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 321 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479536/321-10-50-4 + Details
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