Investments In Securities (Schedule Of Unrealized Losses On Investments) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Government obligations
Debt Securities, Available-for-sale [Line Items]
Total temporarily impaired securities, Less than 12 Months, Fair Value	$ 1,006	$ 1,016
Total temporarily impaired securities, Less than 12 Months, Unrealized Losses	(2)	(7)
Total temporarily impaired securities, 12 Months or Longer, Fair Value	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0
Total temporarily impaired securities, Total Fair Value	1,006	1,016
Total temporarily impaired securities, Unrealized Losses	(2)	(7)
General obligations of U.S. states, territories and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Total temporarily impaired securities, Less than 12 Months, Fair Value		4,888
Total temporarily impaired securities, Less than 12 Months, Unrealized Losses		(32)
Total temporarily impaired securities, 12 Months or Longer, Fair Value		6,469
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		(111)
Total temporarily impaired securities, Total Fair Value		11,357
Total temporarily impaired securities, Unrealized Losses		(143)
Special revenue issuer obligations of U.S. states, territories and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Total temporarily impaired securities, Less than 12 Months, Fair Value	2,160	12,326
Total temporarily impaired securities, Less than 12 Months, Unrealized Losses	(12)	(100)
Total temporarily impaired securities, 12 Months or Longer, Fair Value	1,126	9,720
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(1)	(229)
Total temporarily impaired securities, Total Fair Value	3,286	22,046
Total temporarily impaired securities, Unrealized Losses	(13)	(329)
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Total temporarily impaired securities, Less than 12 Months, Fair Value		4,490
Total temporarily impaired securities, Less than 12 Months, Unrealized Losses		(28)
Total temporarily impaired securities, 12 Months or Longer, Fair Value		3,733
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		(19)
Total temporarily impaired securities, Total Fair Value		8,223
Total temporarily impaired securities, Unrealized Losses		(47)
Total temporarily impaired securities
Debt Securities, Available-for-sale [Line Items]
Total temporarily impaired securities, Less than 12 Months, Fair Value	3,166	22,720
Total temporarily impaired securities, Less than 12 Months, Unrealized Losses	(14)	(167)
Total temporarily impaired securities, 12 Months or Longer, Fair Value	1,126	19,922
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(1)	(359)
Total temporarily impaired securities, Total Fair Value	4,292	42,642
Total temporarily impaired securities, Unrealized Losses	$ (15)	$ (526)