Loans (Aging Of Recorded Investment In Past Due Loans) (Details) $ in Thousands		3 Months Ended			9 Months Ended
		Sep. 30, 2017 USD ($) contracts		Sep. 30, 2016 USD ($) contracts	Sep. 30, 2017 USD ($) contracts		Sep. 30, 2016 USD ($) contracts	Dec. 31, 2016 USD ($)
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Number of Contracts, During Period | contracts		139		115	325		309
Accruing loans past due 30-89 days		$ 22,856			$ 22,856			$ 26,591
Past due nonaccrual loans and loans past due 90 days or more and accruing		28,240	[1]		28,240	[1]		24,050	[2]
Total loans past due		51,096			51,096			50,641
Total current		5,331,247			5,331,247			5,236,189
Recorded Investment		5,382,343			5,382,343			5,286,830
Loans past due 90 days or more and accruing		2,037			2,037			2,138
Impaired Financing Receivable, Recorded Investment, Nonaccrual loans which are current in regards to contractual P&I payments		64,400			64,400			65,900
Financing Receivable, Modifications, Recorded Investment, During Period		$ 4,938		$ 12,422	$ 10,765		$ 18,779
Construction Real Estate Commercial [Domain]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Number of Contracts, During Period | contracts		0		1	0		2
Past due nonaccrual loans and loans past due 90 days or more and accruing	[2]							541
Total loans past due								541
Total current		$ 139,672			$ 139,672			135,200
Recorded Investment		139,672			139,672			135,741
Loans past due 90 days or more and accruing		$ 0			0			0
Financing Receivable, Modifications, Recorded Investment, During Period				$ 947	$ 0		$ 1,144
Commercial Financial And Agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Number of Contracts, During Period | contracts		14		12	25		29
Accruing loans past due 30-89 days		$ 70			$ 70			371
Past due nonaccrual loans and loans past due 90 days or more and accruing		10,527	[1]		10,527	[1]		4,113	[2]
Total loans past due		10,597			10,597			4,484
Total current		1,019,041			1,019,041			993,693
Loans past due 90 days or more and accruing		0			0			15
Financing Receivable, Modifications, Recorded Investment, During Period		$ 1,415		$ 6,603	$ 4,169		$ 7,344
Construction Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Number of Contracts, During Period | contracts		0		0	1		0
Accruing loans past due 30-89 days		$ 213			$ 213			559
Total loans past due		213			213			559
Total current		47,525			47,525			48,246
Recorded Investment		47,738			47,738			48,805
Loans past due 90 days or more and accruing		$ 0			0			0
Financing Receivable, Modifications, Recorded Investment, During Period					$ 8
Construction Real Estate - Installment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Number of Contracts, During Period | contracts		0		0	0		1
Accruing loans past due 30-89 days		$ 11			$ 11			223
Past due nonaccrual loans and loans past due 90 days or more and accruing		48	[1]		48	[1]		64	[2]
Total loans past due		59			59			287
Total current		4,161			4,161			4,633
Recorded Investment		4,220			4,220			4,920
Loans past due 90 days or more and accruing		$ 0			0			12
Financing Receivable, Modifications, Recorded Investment, During Period					$ 0		$ 9
Residential Real Estate - Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Number of Contracts, During Period | contracts		10		4	15		7
Accruing loans past due 30-89 days								330
Past due nonaccrual loans and loans past due 90 days or more and accruing		$ 1,345	[1]		$ 1,345	[1]		3,631	[2]
Total loans past due		1,345			1,345			3,961
Total current		391,116			391,116			403,666
Recorded Investment		392,461			392,461			407,627
Loans past due 90 days or more and accruing		0			0
Financing Receivable, Modifications, Recorded Investment, During Period		$ 498		$ 225	$ 702		$ 918
Residential Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Number of Contracts, During Period | contracts		5		14	24		23
Accruing loans past due 30-89 days		$ 11,305			$ 11,305			10,854
Past due nonaccrual loans and loans past due 90 days or more and accruing		9,354	[1]		9,354	[1]		9,769	[2]
Total loans past due		20,659			20,659			20,623
Total current		1,116,099			1,116,099			1,150,331
Recorded Investment		1,136,758			1,136,758			1,170,954
Loans past due 90 days or more and accruing		882			882			887
Financing Receivable, Modifications, Recorded Investment, During Period		$ 417		$ 1,173	$ 1,669		$ 1,809
Residential Real Estate - HELOC [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Number of Contracts, During Period | contracts		4		2	16		10
Accruing loans past due 30-89 days		$ 400			$ 400			970
Past due nonaccrual loans and loans past due 90 days or more and accruing		917	[1]		917	[1]		1,020	[2]
Total loans past due		1,317			1,317			1,990
Total current		206,244			206,244			211,304
Recorded Investment		207,561			207,561			213,294
Loans past due 90 days or more and accruing		0			0			25
Financing Receivable, Modifications, Recorded Investment, During Period		168		$ 91	529		$ 201
Residential Real Estate - Installment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing loans past due 30-89 days		349			349			350
Past due nonaccrual loans and loans past due 90 days or more and accruing		261	[1]		261	[1]		319	[2]
Total loans past due		610			610			669
Total current		18,575			18,575			19,272
Recorded Investment		19,185			19,185			19,941
Loans past due 90 days or more and accruing		0			0			60
Financing Receivable, Modifications, Recorded Investment, During Period		151		$ 37	216		$ 79
Commercial Financial And Agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment	[3]	$ 1,029,638			$ 1,029,638			998,177
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Number of Contracts, During Period | contracts		3		6	9		10
Accruing loans past due 30-89 days		$ 82			$ 82			355
Past due nonaccrual loans and loans past due 90 days or more and accruing		3,455	[1]		3,455	[1]		2,499	[2]
Total loans past due		3,537			3,537			2,854
Total current		1,156,589			1,156,589			1,157,010
Recorded Investment	[3]	1,160,126			1,160,126			1,159,864
Loans past due 90 days or more and accruing		0			0
Financing Receivable, Modifications, Recorded Investment, During Period		$ 1,455		$ 1,777	$ 2,320		$ 5,118
Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Number of Contracts, During Period | contracts		99		74	228		223
Accruing loans past due 30-89 days		$ 10,426			$ 10,426			12,579
Past due nonaccrual loans and loans past due 90 days or more and accruing		2,333	[1]		2,333	[1]		2,094	[2]
Total loans past due		12,759			12,759			14,673
Total current		1,228,841			1,228,841			1,109,562
Recorded Investment		1,241,600			1,241,600			1,124,235
Loans past due 90 days or more and accruing		1,155			1,155			1,139
Financing Receivable, Modifications, Recorded Investment, During Period		834		$ 1,569	1,152		$ 2,157
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		3,384			3,384			3,272
Recorded Investment		$ 3,384			$ 3,384			$ 3,272
Residential Real Estate - Installment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Number of Contracts, During Period | contracts		4		2	7		4
Accruing Financing Receivable Modifications [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period		$ 2,061		$ 246	$ 3,608		$ 3,214
Accruing Financing Receivable Modifications [Member] | Construction Real Estate Commercial [Domain]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period					0
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		400		152	400		102
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		0		0	0		0
Accruing Financing Receivable Modifications [Member] | Residential Real Estate - Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period		144			144
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		211		0	746		96
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		123		0	478		17
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		110		33	175		72
Accruing Financing Receivable Modifications [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period		974			1,525		2,812
Accruing Financing Receivable Modifications [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period		99		61	140		115
Nonaccruing Financing Receivable Modifications [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period		2,877		12,176	7,157		15,565
Nonaccruing Financing Receivable Modifications [Member] | Construction Real Estate Commercial [Domain]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period				947	0		1,144
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		1,015		6,451	3,769		7,242
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
Nonaccruing Financing Receivable Modifications [Member] | Construction Real Estate - Installment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period					0		9
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		354		225	558		918
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		206		1,173	923		1,713
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		45		91	51		184
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		41		4	41		7
Nonaccruing Financing Receivable Modifications [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period		481		1,777	795		2,306
Nonaccruing Financing Receivable Modifications [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period		$ 735		$ 1,508	$ 1,012		$ 2,042

[1] 1) Includes $2.0 million of loans past due 90 days or more and accruing. The remaining are past due nonaccrual loans.(2) Includes $64.4 million of nonaccrual loans which are current in regards to contractual principal and interest payments

[2] 1) Includes $2.1 million of loans past due 90 days or more and accruing. The remaining are past due nonaccrual loans.(2) Includes $65.9 million of nonaccrual loans which are 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.