Securities (Summary Of Securities Available For Sale In Unrealized Loss Position) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, Estimated Fair Value	$ 112,976	$ 65,199
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(2,358)	(550)
12 months or more, Estimated Fair Value	26,239	37,384
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(1,097)	(964)
Total Estimated Fair Value	139,215	102,583
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(3,455)	(1,514)
Temporarily Impaired Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, Estimated Fair Value	112,976	65,199
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(2,358)	(550)
12 months or more, Estimated Fair Value	26,239	37,384
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(1,097)	(964)
Total Estimated Fair Value	139,215	102,583
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(3,455)	(1,514)
Temporarily Impaired Securities [Member] | U S Government Corporations And Agencies Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, Estimated Fair Value	19,787	10,864
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(318)	(91)
12 months or more, Estimated Fair Value	2,003	2,394
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(54)	(54)
Total Estimated Fair Value	21,790	13,258
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(372)	(145)
Temporarily Impaired Securities [Member] | Government Sponsored Agencies [Member]
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, Estimated Fair Value	17,563	32,156
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(559)	(269)
12 months or more, Estimated Fair Value	15,311	22,584
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(740)	(634)
Total Estimated Fair Value	32,874	54,740
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(1,299)	(903)
Temporarily Impaired Securities [Member] | Nongovernment Sponsored Agencies [Member]
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, Estimated Fair Value	13	5
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	0
12 months or more, Estimated Fair Value	585	810
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(5)	(7)
Total Estimated Fair Value	598	815
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(5)	(7)
Temporarily Impaired Securities [Member] | State and Political Subdivisions General Obligations [Member]
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, Estimated Fair Value	5,878	6,035
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(208)	(55)
12 months or more, Estimated Fair Value	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0
Total Estimated Fair Value	5,878	6,035
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(208)	(55)
Temporarily Impaired Securities [Member] | State and Political Subdivisions Other Revenues [Member]
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, Estimated Fair Value	11,474	7,532
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(344)	(62)
12 months or more, Estimated Fair Value	781	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(28)	0
Total Estimated Fair Value	12,255	7,532
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(372)	(62)
Temporarily Impaired Securities [Member] | Corporate Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, Estimated Fair Value	960	3,008
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(40)	(39)
12 months or more, Estimated Fair Value	3,661	1,659
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(128)	(91)
Total Estimated Fair Value	4,621	4,667
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(168)	(130)
Temporarily Impaired Securities [Member] | Tax Exempt State and Political Subdivisions General Obligations [Member]
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, Estimated Fair Value	26,460	2,999
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(370)	(20)
12 months or more, Estimated Fair Value	3,898	9,937
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(142)	(178)
Total Estimated Fair Value	30,358	12,936
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(512)	(198)
Temporarily Impaired Securities [Member] | Tax Exempt State and Political Subdivisions Water and Sewer Revenues [Member]
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, Estimated Fair Value	5,960	282
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(105)	(3)
12 months or more, Estimated Fair Value	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0
Total Estimated Fair Value	5,960	282
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(105)	(3)
Temporarily Impaired Securities [Member] | Tax Exempt State and Political Subdivisions Lease Revenues [Member]
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, Estimated Fair Value	1,121	569
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(4)	(2)
12 months or more, Estimated Fair Value	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0
Total Estimated Fair Value	1,121	569
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(4)	(2)
Temporarily Impaired Securities [Member] | Tax Exempt State and Political Subdivisions Sales Tax Revenues [Member]
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, Estimated Fair Value	2,265
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(29)
12 months or more, Estimated Fair Value	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0
Total Estimated Fair Value	2,265
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(29)
Temporarily Impaired Securities [Member] | Tax Exempt State and Political Subdivisions University Revenues [Member]
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, Estimated Fair Value		1,749
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		(9)
12 months or more, Estimated Fair Value		0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		0
Total Estimated Fair Value		1,749
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		$ (9)
Temporarily Impaired Securities [Member] | Tax Exempt State and Political Subdivisions Other Revenues [Member]
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, Estimated Fair Value	21,495
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(381)
12 months or more, Estimated Fair Value	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0
Total Estimated Fair Value	21,495
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ (381)