Investments (Summary Of Components Of Net Investment Income) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Schedule of Available-for-sale Securities [Line Items]
Gross investment income before adjustments	$ 244,520	$ 189,229	$ 444,688	$ 523,050
Funds held interest income (expense)	684	2,325	10,921	9,715
Future policy benefit reserve income (expense)	(291)	(372)	(805)	(965)
Gross investment income	244,913	191,182	454,804	531,800
Investment expenses	(10,680)	(10,124)	(34,688)	(30,738)
Net investment income	234,233	181,058	420,116	501,062
Fixed Maturity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income before adjustments	136,104	130,139	407,946	383,440
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income before adjustments	4,402	4,147	11,585	12,250
Short-Term Investments and Cash [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income before adjustments	494	3,899	4,356	13,497
Limited Partnerships [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income before adjustments	88,778	43,758	22,092	100,298
Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross investment income before adjustments	$ 14,742	$ 7,286	$ (1,291)	$ 13,565