Investments (Components Of Net Investment Income) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Dividends on equity securities	$ 36,739	$ 31,134	$ 101,263	$ 84,968
Total investment income	240,354	196,266	691,001	534,070
Investment expenses	(4,877)	(4,059)	(14,194)	(12,835)
Net investment income	235,477	192,207	676,807	521,235
Fixed Maturity Securities [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Interest income	131,424	98,891	372,089	269,438
Short-term investments [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Interest income	30,971	26,768	94,809	77,099
Cash and Cash Equivalents
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Interest income	$ 41,220	$ 39,473	$ 122,840	$ 102,565