Investments (Summary Of Changes In Net Unrealized Appreciation (Depreciation) For The Company's Investments) (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]
Change in unrealized appreciation (depreciation), pre-tax	$ 63,124	$ 311,927	$ (74,026)	$ 123,520
Deferred tax benefit (expense)	(13,272)	(64,834)	15,510	(26,065)
Total URA(D) on securities arising during the period	49,852	247,093	(58,516)	97,455
Fixed Maturity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Change in unrealized appreciation (depreciation), pre-tax	$ 63,124	$ 311,927	$ (74,026)	$ 123,520