The amount by which the fair value of an investment is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

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Investments (Summary Of Components Of Net Realized Capital Gains (Losses)) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Other-than-temporary impairments									$ (20,899)	$ (8,110)	$ (7,093)
Total net realized capital gains (losses)	$ 75,443	$ (12,943)	$ 30,272	$ 92,232	$ (172,815)	$ 54,804	$ 15,776	$ (24,901)	185,004	(127,136)	153,194
Fixed Maturity Securities [Member] \| Market Value [Member]
Schedule of Available-for-sale Securities [Line Items]
Other-than-temporary impairments									(20,899)	(8,110)	(7,093)
Gains (losses) from sales									28,025	(21,719)	17,714
Fixed Maturity Securities [Member] \| Fair Value [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains (losses) from sales									355	(1,799)
Gains (losses) from fair value adjustments									1,808	1,506
Equity Securities [Member] \| Market Value [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains (losses) from sales											(3,424)
Equity Securities [Member] \| Fair Value [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains (losses) from sales									4,148	(29,941)	6,969
Gains (losses) from fair value adjustments									165,200	(68,832)	138,973
Other Invested Assets [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains (losses) from sales									6,003	1,815	61
Short-Term Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains (losses) from sales									$ 364	$ (56)	$ (6)