Investments In Securities and Fair Value (Schedule Of Gross Realized and Unrealized Gains And Losses On Securities) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Marketable Security, Gain (Loss) [Abstract]
Equity securities, realized gains	$ 6,217	$ 2,809	$ 13,700	$ 4,556
Debit and equity securities, realized gains	6,217	2,809	13,700	4,556
Debt Securities, Available-for-sale, Realized Loss	0	(46)	0	(46)
Equity securities, realized losses	(202)	(189)	(323)	(189)
Write-down of securities	(30)	(127)	(112)	(127)
Debt and Equity Securities, Realized Loss	(232)	(362)	(435)	(362)
Debt and equity securities, net realized gain (loss)	5,985	2,447	13,265	4,194
Gross losses on sales of other investments	(69)	(409)	(116)	(409)
Net gains (losses) on sales of other investments	(69)	(409)	(116)	(409)
Net realized investment gains (losses)	5,916	2,038	13,149	3,785
Unrealized Gain (Loss) on Investments	(4,824)	(12,172)	(11,614)	(18,087)
Gain (Loss) on Investments	$ 1,092	$ (10,134)	$ 1,535	$ (14,302)