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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
	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

The net gains or losses on investments during the period, also including gains or losses on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity.

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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).

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-Topic 320
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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).

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Amount of realized gain (loss) from sale of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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