Investments (Aggregate Carrying And Approximate Market Values Of Available-For-Sale Securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 560,512	$ 551,103
Gross Unrealized Gains	1,298	7,211
Gross Unrealized Losses	16,182	7,925
Estimated Fair Value	545,628	550,389
U.S Treasuries and U.S. Government Agencies
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1	2
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	1	2
Obligations Of States And Political Subdivisions
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	94,474	94,552
Gross Unrealized Gains	709	2,051
Gross Unrealized Losses	1,010	407
Estimated Fair Value	94,173	96,196
U.S. Government Agencies Mortgage-backed Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	442,044	425,559
Gross Unrealized Gains	462	1,093
Gross Unrealized Losses	15,112	7,305
Estimated Fair Value	427,394	419,347
Private Label
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	599	649
Gross Unrealized Gains	3	3
Gross Unrealized Losses	0	0
Estimated Fair Value	602	652
Trust Preferred Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	4,767	4,764
Gross Unrealized Gains	26	26
Gross Unrealized Losses	0	54
Estimated Fair Value	4,793	4,736
Corporate Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	17,102	21,916
Gross Unrealized Gains	98	475
Gross Unrealized Losses	0	123
Estimated Fair Value	17,200	22,268
Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	558,987	547,442
Gross Unrealized Gains	1,298	3,648
Gross Unrealized Losses	16,122	7,889
Estimated Fair Value	544,163	543,201
Equity Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		2,136
Gross Unrealized Gains		3,563
Gross Unrealized Losses		0
Estimated Fair Value		5,699
Money Market Funds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,525	1,525
Gross Unrealized Gains	0	0
Gross Unrealized Losses	60	36
Estimated Fair Value	$ 1,465	$ 1,489

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=75030427&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27232-111563

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-Section 45
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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.2)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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