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Investments (Net Investment Gains (Losses) and Change in Net Unrealized Gains On Available-For-Sale Investments) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Gain (Loss) on Securities [Line Items]
Net realized investment gains (losses)	$ 4,423	$ (42,177)	$ (40,983)
Change in fair value of equity securities sold during the period	(14,966)	34,684	(14,884)
Change in fair value of equity securities held at the end of the period	1,817,762	1,531,547	(1,539,866)
Change in fair value of equity securities	1,802,796	1,566,231	(1,554,750)
Net investment gains (losses)	1,807,219	1,524,054	(1,595,733)
Change in net unrealized gains on investments included in other comprehensive income (loss)	(165,423)	390,558	(1,463,876)
Fixed maturities [Member]
Gain (Loss) on Securities [Line Items]
Change in net unrealized gains on investments included in other comprehensive income (loss)	(152,630)	389,498	(1,474,890)
Short-term investments [Member]
Gain (Loss) on Securities [Line Items]
Change in net unrealized gains on investments included in other comprehensive income (loss)	$ (12,793)	$ 1,060	$ 11,014

X

- 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 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
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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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Amount of unrealized 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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Amount, before tax and after adjustment, of unrealized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale) and unrealized gain (loss) on investment in debt security measured at amortized cost (held-to-maturity) from transfer to available-for-sale.

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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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