Investments (Summary Of Components Of Net Investment Income) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Schedule of Available-for-sale Securities [Line Items]
Gross investment income before adjustments	$ 418,349	$ 48,051	$ 684,635	$ 200,168
Funds held interest income (expense)	3,287	2,021	11,253	10,237
Future policy benefit reserve income (expense)	(170)	(303)	(461)	(514)
Gross investment income	421,466	49,769	695,427	209,891
Investment expenses	(14,371)	(11,686)	(27,919)	(24,008)
Net investment income	407,095	38,083	667,508	185,883
Fixed Maturity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income before adjustments	148,262	133,918	289,178	271,842
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income before adjustments	3,493	3,662	8,331	7,183
Short Term Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income before adjustments	773	1,687	953	3,862
Limited Partnerships [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income before adjustments	239,966	(88,254)	354,299	(66,686)
Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income before adjustments	$ 25,855	$ (2,962)	$ 31,874	$ (16,033)