Fair Value Of Financial Instruments (Schedule Of Changes In Fair Value Associated With Level 3 Financial Instruments) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2022
Asset-Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 53,416	$ 64,706
Unrealized gains/(losses)		4,750
Realized gains	104	1,777
Purchases	1,590	1,590
Redemptions	9,899	27,612
Net change	(8,205)	(19,495)
Ending Balance	45,211	45,211
Corporate Equity Securities Financial Instruments Owned [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	1,013	225
Unrealized gains/(losses)		839
Realized gains		336
Sales		(387)
Net change	0	788
Ending Balance	1,013	1,013
Loans [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	34,960	26,857
Unrealized gains/(losses)	152	212
Realized gains	243	568
Purchases	74,982	108,204
Sales	(8,318)	(33,218)
Redemptions	1,832	2,436
Net change	65,227	73,330
Ending Balance	100,187	100,187
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	0	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	13,743	13,032
Unrealized gains/(losses)	222	933
Net change	222	933
Ending Balance	13,965	13,965
Other Investment [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	34,725	35,837
Unrealized gains/(losses)	54	(1,012)
Realized gains	0	992
Sales		(999)
Redemptions		39
Net change	54	(1,058)
Ending Balance	$ 34,779	$ 34,779