Fair Value Of Financial Instruments (Schedule Of Changes In Fair Value Associated With Level 3 Financial Instruments) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Asset-Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 2,179	$ 64,706
Unrealized gains/(losses)		4,789
Realized gains/(losses)	1,007	4,287
Purchases		4,820
Redemptions	(1,688)	(76,423)
Net change	(681)	(62,527)
Ending Balance	1,498	2,179
Corporate Equity Securities Financial Instruments Owned [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		225
Realized gains/(losses)		1,621
Sales		(1,846)
Net change		(225)
Syndicated Loans [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	69,888	26,857
Unrealized gains/(losses)	(15)	550
Realized gains/(losses)	(2,161)	2,653
Purchases	69,881	227,548
Sales	(35,988)	(177,895)
Redemptions	(18,641)	(9,825)
Net change	13,076	43,031
Ending Balance	82,964	69,888
Corporate Equity Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	11,878	5,754
Unrealized gains/(losses)		6,124
Net change		6,124
Ending Balance	11,878	11,878
Auction Rate Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	14,681	13,032
Unrealized gains/(losses)	2	1,649
Realized gains/(losses)	(232)
Redemptions	(13,668)
Net change	(13,898)	1,649
Ending Balance	783	14,681
Other Investment [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	36,974	35,837
Unrealized gains/(losses)	993	1,183
Realized gains/(losses)		992
Purchases	1,500
Sales		(999)
Redemptions		(39)
Net change	2,493	1,137
Ending Balance	$ 39,467	$ 36,974