Investments (Summary Of Components Of Net Realized Capital Gains (Losses)) (Details) - USD ($)	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]
Other-than-temporary impairments		$ (7,314,000)		$ (15,404,000)
Total net realized capital gains (losses)	110,203,000	(12,943,000)	84,263,000	109,561,000
Beginning Balance	(25,837,000)		0
Credit losses on securities where credit losses were not previously recorded	(150,000)		(32,884,000)
Increases in allowance on previously impaired securities	(5,562,000)		(6,644,000)
Decrease in allowance on previously impaired securities	310,000		4,646,000
Reduction in allowance due to disposals	11,598,000		15,241,000
Balance as of September 30, 2020	(19,641,000)		(19,641,000)
Fixed Maturity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Balance as of September 30, 2020	(19,641,000)		(19,641,000)
Fixed Maturity Securities [Member] | Market Value [Member]
Schedule of Available-for-sale Securities [Line Items]
Allowance for credit losses	6,196,000		19,641,000
Other-than-temporary impairments		(7,314,000)		(15,404,000)
Gains (losses) from sales	5,398,000	5,290,000	941,000	16,660,000
Fixed Maturity Securities [Member] | Fair Value [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains (losses) from sales	(1,968,000)		(1,968,000)	356,000
Gains (losses) from fair value adjustments	3,339,000		1,944,000	13,000
Corporate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Beginning Balance	(22,253,000)
Credit losses on securities where credit losses were not previously recorded	(6,000)		(27,666,000)
Increases in allowance on previously impaired securities	(5,354,000)		(6,136,000)
Decrease in allowance on previously impaired securities	159,000		3,590,000
Reduction in allowance due to disposals	9,980,000		12,738,000
Balance as of September 30, 2020	(17,474,000)		(17,474,000)
Equity Securities [Member] | Fair Value [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains (losses) from sales	(1,317,000)	(1,192,000)	(12,642,000)	2,541,000
Gains (losses) from fair value adjustments	96,673,000	(12,008,000)	114,364,000	102,795,000
Other Invested Assets [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains (losses) from sales	1,084,000	2,098,000	50,000	2,341,000
Short-Term Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains (losses) from sales	798,000	$ 183,000	1,215,000	$ 259,000
Foreign Government Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Beginning Balance	(92,000)
Credit losses on securities where credit losses were not previously recorded			(519,000)
Increases in allowance on previously impaired securities	(27,000)		(27,000)
Decrease in allowance on previously impaired securities			212,000
Reduction in allowance due to disposals			215,000
Balance as of September 30, 2020	(119,000)		(119,000)
Foreign Corporate [Member]
Schedule of Available-for-sale Securities [Line Items]
Beginning Balance	(3,492,000)
Credit losses on securities where credit losses were not previously recorded	(144,000)		(4,699,000)
Increases in allowance on previously impaired securities	(181,000)		(481,000)
Decrease in allowance on previously impaired securities	151,000		844,000
Reduction in allowance due to disposals	1,618,000		2,288,000
Balance as of September 30, 2020	$ (2,048,000)		$ (2,048,000)