Investments (Summary Of Components Of Net Realized Capital Gains (Losses)) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Schedule of Available-for-sale Securities [Line Items]
Total net realized capital gains (losses)	$ (4,222)	$ 110,203	$ 138,789	$ 84,263
Beginning Balance	(24,650)	(25,837)	(1,745)
Credit losses on securities where credit losses were not previously recorded	(5,408)	(150)	(27,298)	(32,884)
Increases in allowance on previously impaired securities	(3,384)	(5,562)	(4,852)	(6,644)
Decrease in allowance on previously impaired securities		310		4,646
Reduction in allowance due to disposals	1,462	11,598	1,915	15,241
Ending Balance	(31,980)	(19,641)	(31,980)	(19,641)
Fixed Maturity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Beginning Balance			(1,745)
Ending Balance	(31,980)		(31,980)
Fixed Maturity Securities [Member] \| Market Value [Member]
Schedule of Available-for-sale Securities [Line Items]
Allowance for credit losses	(7,329)	6,196	(30,234)	(19,641)
Gains (losses) from sales	6,219	5,398	25,453	941
Fixed Maturity Securities [Member] \| Fair Value [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains (losses) from sales		(1,968)		(1,968)
Gains (losses) from fair value adjustments		3,339		1,944
Corporate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Beginning Balance	(18,475)	(22,253)	(1,220)
Credit losses on securities where credit losses were not previously recorded	(5,257)	(6)	(21,177)	(27,666)
Increases in allowance on previously impaired securities	(620)	(5,354)	(2,088)	(6,136)
Decrease in allowance on previously impaired securities		159		3,590
Reduction in allowance due to disposals	1,462	9,980	1,595	12,738
Ending Balance	(22,890)	(17,474)	(22,890)	(17,474)
Equity Securities [Member] \| Fair Value [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains (losses) from sales	(489)	(1,317)	9,504	(12,642)
Gains (losses) from fair value adjustments	(4,542)	96,673	128,039	114,364
Other Invested Assets [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains (losses) from sales	1,920	1,084	6,014	50
Short-Term Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains (losses) from sales		798	13	1,215
Asset Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Beginning Balance	(4,915)
Credit losses on securities where credit losses were not previously recorded			(4,915)
Increases in allowance on previously impaired securities	(2,764)		(2,764)
Decrease in allowance on previously impaired securities
Reduction in allowance due to disposals
Ending Balance	(7,679)		(7,679)
Obligations Of U.S. States And Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Beginning Balance
Credit losses on securities where credit losses were not previously recorded	(151)		(151)
Increases in allowance on previously impaired securities
Decrease in allowance on previously impaired securities
Reduction in allowance due to disposals
Ending Balance	(151)		(151)
Foreign Government Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Beginning Balance		(92)	(22)
Credit losses on securities where credit losses were not previously recorded				(519)
Increases in allowance on previously impaired securities		(27)		(27)
Decrease in allowance on previously impaired securities				212
Reduction in allowance due to disposals			22	215
Ending Balance		(119)		(119)
Foreign Corporate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Beginning Balance	(1,260)	(3,492)	(503)
Credit losses on securities where credit losses were not previously recorded		(144)	(1,055)	(4,699)
Increases in allowance on previously impaired securities		(181)		(481)
Decrease in allowance on previously impaired securities		151		844
Reduction in allowance due to disposals		1,618	298	2,288
Ending Balance	$ (1,260)	$ (2,048)	$ (1,260)	$ (2,048)

Amount of allowance for credit 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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