Fair Value Of Financial Instruments (Schedule Of Changes In Fair Value Associated With Level 3 Financial Instruments) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($)
Asset-Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 175
Ending Balance	175
Loans [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	9,151
Unrealized losses	(2,827)
Purchases	6,942
Sales	(3,004)
Redemptions	(3)
Net change	1,108
Ending Balance	10,259
Corporate Equity Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	1,060
Ending Balance	1,060
Equity Auction Rate Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	14,243
Ending Balance	14,243
Auction Rate Municipal Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	184
Unrealized losses	(1)
Net change	(1)
Ending Balance	183
Other Investment [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	853
Sales	(20)
Net change	(20)
Ending Balance	$ 833