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, 2020	Jun. 30, 2020
Asset-Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 175	$ 175
Ending Balance	175	175
Loans [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	10,259	9,151
Unrealized losses	(786)	(3,613)
Purchases	139	7,081
Sales	(1)	(3,005)
Redemptions		(3)
Net change	(648)	460
Ending Balance	9,611	9,611
Corporate Equity Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	1,060	1,060
Ending Balance	1,060	1,060
Equity Auction Rate Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	14,243	14,243
Unrealized losses	(1,622)	(1,622)
Net change	(1,622)	(1,622)
Ending Balance	12,621	12,621
Auction Rate Municipal Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	183	184
Unrealized losses		(1)
Net change		(1)
Ending Balance	183	183
Other Investment [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	833	853
Unrealized losses	(478)	(478)
Sales		(20)
Transfers into Level 3	34,646	34,646
Net change	34,168	34,148
Ending Balance	$ 35,001	$ 35,001