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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 | 6 Months Ended
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Jun. 30, 2025 | Jun. 30, 2024 | Jun. 30, 2025 | Jun. 30, 2024
Gain (Loss) on Securities [Line Items] |  |  |  |
Net realized investment losses | $ (16,596) | $ (14,007) | $ (18,397) | $ (18,495)
Change in fair value of securities sold during the period | 1,134 | (4,654) | (188) | (4,611)
Change in fair value of securities held at the end of the period | 595,685 | (111,356) | 449,737 | 795,370
Total change in fair value of equity securities | 596,819 | (116,010) | 449,549 | 790,759
Net investment gains (losses) | 580,223 | (130,017) | 431,152 | 772,264
Change in net unrealized losses on available-for-sale investments included in other comprehensive income (loss): | 258,329 | (36,598) | 535,556 | (192,367)
Fixed Maturity Securities [Member] |  |  |  |
Gain (Loss) on Securities [Line Items] |  |  |  |
Change in net unrealized losses on available-for-sale investments included in other comprehensive income (loss): | 251,805 | (36,240) | 525,018 | (184,727)
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): | $ 6,524 | $ (358) | $ 10,538 | $ (7,640)

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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/1943274/2147477250/944-220-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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