Loans (Aging Of Recorded Investment In Past Due Loans) (Details) - USD ($) $ in Thousands		3 Months Ended			6 Months Ended
		Jun. 30, 2018		Jun. 30, 2017	Jun. 30, 2018		Jun. 30, 2017	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing loans past due 30-89 days		$ 26,729			$ 26,729			$ 25,241
Past due nonaccrual loans and loans past due 90 days or more and accruing		29,158	[1]		29,158	[1]		17,776	[2]
Total loans past due		55,887			55,887			43,017
Total current		5,285,668			5,285,668			5,346,125
Recorded Investment		5,341,555			5,341,555			5,389,142
Loans past due 90 days or more and accruing		1,478			1,478			1,845
Impaired Financing Receivable, Recorded Investment, Nonaccrual loans which are current in regards to contractual P&I payments		53,400			53,400			56,100
Financing Receivable, Modifications, Recorded Investment, During Period		2,374		$ 3,036	3,767		$ 7,569
Construction Real Estate Commercial [Domain]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing loans past due 30-89 days		41			41			29
Past due nonaccrual loans and loans past due 90 days or more and accruing	[1]	1,821			1,821
Total loans past due		1,862			1,862			29
Total current		134,619			134,619			125,761
Recorded Investment		136,481			136,481			125,790
Loans past due 90 days or more and accruing		0			0			0
Commercial Financial And Agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing loans past due 30-89 days		3,556			3,556			145
Past due nonaccrual loans and loans past due 90 days or more and accruing		12,913	[1]		12,913	[1]		1,043	[2]
Total loans past due		16,469			16,469			1,188
Total current		1,002,920			1,002,920			1,056,678
Loans past due 90 days or more and accruing		6			6
Financing Receivable, Modifications, Recorded Investment, During Period		149		164	193		3,052
Construction Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing loans past due 30-89 days		506			506			256
Total loans past due		506			506			256
Total current		52,516			52,516			52,080
Recorded Investment		53,022			53,022			52,336
Loans past due 90 days or more and accruing		0			0			0
Financing Receivable, Modifications, Recorded Investment, During Period				8			8
Construction Real Estate - Installment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing loans past due 30-89 days		39			39			54
Past due nonaccrual loans and loans past due 90 days or more and accruing		17	[1]		17	[1]		19	[2]
Total loans past due		56			56			73
Total current		2,918			2,918			3,818
Recorded Investment		2,974			2,974			3,891
Loans past due 90 days or more and accruing		0			0			0
Financing Receivable, Modifications, Recorded Investment, During Period		14			14
Residential Real Estate - Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing loans past due 30-89 days								16
Past due nonaccrual loans and loans past due 90 days or more and accruing		1,112	[1]		1,112	[1]		1,586	[2]
Total loans past due		1,112			1,112			1,602
Total current		390,608			390,608			392,521
Recorded Investment		391,720			391,720			394,123
Loans past due 90 days or more and accruing		0			0
Financing Receivable, Modifications, Recorded Investment, During Period				282			282
Residential Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing loans past due 30-89 days		12,214			12,214			11,515
Past due nonaccrual loans and loans past due 90 days or more and accruing		8,169	[1]		8,169	[1]		9,232	[2]
Total loans past due		20,383			20,383			20,747
Total current		1,075,632			1,075,632			1,091,195
Recorded Investment		1,096,015			1,096,015			1,111,942
Loans past due 90 days or more and accruing		399			399			568
Financing Receivable, Modifications, Recorded Investment, During Period		317		944	961		1,548
Residential Real Estate - HELOC [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing loans past due 30-89 days		500			500			616
Past due nonaccrual loans and loans past due 90 days or more and accruing		768	[1]		768	[1]		876	[2]
Total loans past due		1,268			1,268			1,492
Total current		188,316			188,316			202,660
Recorded Investment		189,584			189,584			204,152
Loans past due 90 days or more and accruing		60			60			14
Financing Receivable, Modifications, Recorded Investment, During Period		452		208	791		406
Residential Real Estate - Installment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing loans past due 30-89 days		190			190			239
Past due nonaccrual loans and loans past due 90 days or more and accruing		322	[1]		322	[1]		253	[2]
Total loans past due		512			512			492
Total current		16,136			16,136			18,087
Recorded Investment		16,648			16,648			18,579
Loans past due 90 days or more and accruing		103			103			7
Financing Receivable, Modifications, Recorded Investment, During Period		75		40	121		73
Commercial Financial And Agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment	[3]	1,019,389			1,019,389			1,057,866
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing loans past due 30-89 days		156			156			856
Past due nonaccrual loans and loans past due 90 days or more and accruing		2,104	[1]		2,104	[1]		2,360	[2]
Total loans past due		2,260			2,260			3,216
Total current		1,152,826			1,152,826			1,168,674
Recorded Investment	[3]	1,155,086			1,155,086			1,171,890
Loans past due 90 days or more and accruing		0			0
Financing Receivable, Modifications, Recorded Investment, During Period		589		802	720		1,183
Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing loans past due 30-89 days		9,527			9,527			11,515
Past due nonaccrual loans and loans past due 90 days or more and accruing		1,932	[1]		1,932	[1]		2,407	[2]
Total loans past due		11,459			11,459			13,922
Total current		1,266,487			1,266,487			1,231,622
Recorded Investment		1,277,946			1,277,946			1,245,544
Loans past due 90 days or more and accruing		910			910			1,256
Financing Receivable, Modifications, Recorded Investment, During Period		778		588	967		1,017
Leases [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing loans past due 30-89 days		0			0			0
Past due nonaccrual loans and loans past due 90 days or more and accruing		0	[1]		0	[1]		0	[2]
Total loans past due		0			0			0
Total current		2,690			2,690			3,029
Recorded Investment		2,690			2,690			$ 3,029
Accruing Financing Receivable Modifications [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period		1,223		1,477	1,511		1,725
Accruing Financing Receivable Modifications [Member] | Commercial Financial And Agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period		123			123
Accruing Financing Receivable Modifications [Member] | Construction Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period		0		0	0		0
Accruing Financing Receivable Modifications [Member] | Construction Real Estate - Installment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period		14		0	14		0
Accruing Financing Receivable Modifications [Member] | Residential Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period		93		438	93		438
Accruing Financing Receivable Modifications [Member] | Residential Real Estate - HELOC [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period		409		160	661		359
Accruing Financing Receivable Modifications [Member] | Residential Real Estate - Installment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period		71		40	104		73
Accruing Financing Receivable Modifications [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period		455		802	455		803
Accruing Financing Receivable Modifications [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period		58		37	61		52
Nonaccruing Financing Receivable Modifications [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period		1,151		1,559	2,256		5,844
Nonaccruing Financing Receivable Modifications [Member] | Commercial Financial And Agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period		26		164	70		3,052
Nonaccruing Financing Receivable Modifications [Member] | Construction Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period				8			8
Nonaccruing Financing Receivable Modifications [Member] | Residential Real Estate - Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period				282			282
Nonaccruing Financing Receivable Modifications [Member] | Residential Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period		224		506	868		1,110
Nonaccruing Financing Receivable Modifications [Member] | Residential Real Estate - HELOC [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period		43		48	130		47
Nonaccruing Financing Receivable Modifications [Member] | Residential Real Estate - Installment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period		4			17
Nonaccruing Financing Receivable Modifications [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period		134			265		380
Nonaccruing Financing Receivable Modifications [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period		$ 720		$ 551	$ 906		$ 965

[1] 1) Includes $1.5 million of loans past due 90 days or more and accruing. The remaining loans were past due nonaccrual loans.(2) Includes $53.4 million of nonaccrual loans which were current in regards to contractual principal and interest payments

[2] 1) Includes $1.8 million of loans past due 90 days or more and accruing. The remaining loans were past due nonaccrual loans.(2) Includes $56.1 million of nonaccrual loans which were current in regards to contractual principal and interest payments.

[3] Included within each of commercial, financial and agricultural loans and commercial real estate loans is an immaterial amount of consumer loans that are not broken out by class.