Loans (Aging Of Recorded Investment In Past Due Loans) (Details) - USD ($) $ in Thousands		3 Months Ended			9 Months Ended
		Sep. 30, 2018		Sep. 30, 2017	Sep. 30, 2018		Sep. 30, 2017	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing loans past due 30-89 days		$ 28,276			$ 28,276			$ 25,241
Past due nonaccrual loans and loans past due 90 days or more and accruing		18,161	[1]		18,161	[1]		17,776	[2]
Total loans past due		46,437			46,437			43,017
Total current		5,597,996			5,597,996			5,346,125
Recorded Investment		5,644,433			5,644,433			5,389,142
Loans past due 90 days or more and accruing		2,083			2,083			1,845
Impaired Financing Receivable, Recorded Investment, Nonaccrual loans which are current in regards to contractual P&I payments		50,100			50,100			56,100
Financing Receivable, Modifications, Recorded Investment, During Period		3,704		$ 4,938	6,566		$ 10,765
Construction Real Estate Commercial [Domain]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing loans past due 30-89 days								29
Past due nonaccrual loans and loans past due 90 days or more and accruing	[1]	1,837			1,837
Total loans past due		1,837			1,837			29
Total current		150,394			150,394			125,761
Recorded Investment		152,231			152,231			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		2,769			2,769			145
Past due nonaccrual loans and loans past due 90 days or more and accruing		1,817	[1]		1,817	[1]		1,043	[2]
Total loans past due		4,586			4,586			1,188
Total current		1,032,520			1,032,520			1,056,678
Loans past due 90 days or more and accruing		16			16
Financing Receivable, Modifications, Recorded Investment, During Period		574		1,415	800		4,169
Construction Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing loans past due 30-89 days		241			241			256
Total loans past due		241			241			256
Total current		65,759			65,759			52,080
Recorded Investment		66,000			66,000			52,336
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]
Accruing loans past due 30-89 days		179			179			54
Past due nonaccrual loans and loans past due 90 days or more and accruing		21	[1]		21	[1]		19	[2]
Total loans past due		200			200			73
Total current		2,405			2,405			3,818
Recorded Investment		2,605			2,605			3,891
Loans past due 90 days or more and accruing		0			0			0
Financing Receivable, Modifications, Recorded Investment, During Period					12
Residential Real Estate Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing loans past due 30-89 days		79			79			16
Past due nonaccrual loans and loans past due 90 days or more and accruing		1,268	[1]		1,268	[1]		1,586	[2]
Total loans past due		1,347			1,347			1,602
Total current		402,956			402,956			392,521
Recorded Investment		404,303			404,303			394,123
Loans past due 90 days or more and accruing		0			0
Financing Receivable, Modifications, Recorded Investment, During Period		304		498	304		702
Residential Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing loans past due 30-89 days		13,669			13,669			11,515
Past due nonaccrual loans and loans past due 90 days or more and accruing		8,241	[1]		8,241	[1]		9,232	[2]
Total loans past due		21,910			21,910			20,747
Total current		1,120,457			1,120,457			1,091,195
Recorded Investment		1,142,367			1,142,367			1,111,942
Loans past due 90 days or more and accruing		720			720			568
Financing Receivable, Modifications, Recorded Investment, During Period		246		417	1,062		1,669
Residential Real Estate - HELOC [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing loans past due 30-89 days		749			749			616
Past due nonaccrual loans and loans past due 90 days or more and accruing		1,089	[1]		1,089	[1]		876	[2]
Total loans past due		1,838			1,838			1,492
Total current		220,758			220,758			202,660
Recorded Investment		222,596			222,596			204,152
Loans past due 90 days or more and accruing		144			144			14
Financing Receivable, Modifications, Recorded Investment, During Period		469		168	860		529
Residential Real Estate - Installment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing loans past due 30-89 days		273			273			239
Past due nonaccrual loans and loans past due 90 days or more and accruing		212	[1]		212	[1]		253	[2]
Total loans past due		485			485			492
Total current		15,114			15,114			18,087
Recorded Investment		15,599			15,599			18,579
Loans past due 90 days or more and accruing		0			0			7
Financing Receivable, Modifications, Recorded Investment, During Period		336		151	453		216
Commercial Financial And Agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment	[3]	1,037,106			1,037,106			1,057,866
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing loans past due 30-89 days		96			96			856
Past due nonaccrual loans and loans past due 90 days or more and accruing		1,425	[1]		1,425	[1]		2,360	[2]
Total loans past due		1,521			1,521			3,216
Total current		1,306,278			1,306,278			1,168,674
Recorded Investment	[3]	1,307,799			1,307,799			1,171,890
Loans past due 90 days or more and accruing		0			0
Financing Receivable, Modifications, Recorded Investment, During Period		1,154		1,455	1,859		2,320
Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing loans past due 30-89 days		10,221			10,221			11,515
Past due nonaccrual loans and loans past due 90 days or more and accruing		2,251	[1]		2,251	[1]		2,407	[2]
Total loans past due		12,472			12,472			13,922
Total current		1,278,683			1,278,683			1,231,622
Recorded Investment		1,291,155			1,291,155			1,245,544
Loans past due 90 days or more and accruing		1,203			1,203			1,256
Financing Receivable, Modifications, Recorded Investment, During Period		621		834	1,216		1,152
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		2,672			2,672			3,029
Recorded Investment		2,672			2,672			$ 3,029
Accruing Financing Receivable Modifications [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period		897		2,061	2,043		3,608
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		22		400	208		400
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	12		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		55		144	55		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		0		211	90		746
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		453		123	735		478
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		336		110	437		175
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	447		1,525
Accruing Financing Receivable Modifications [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period		31		99	59		140
Nonaccruing Financing Receivable Modifications [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period		2,807		2,877	4,523		7,157
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		552		1,015	592		3,769
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] | Residential Real Estate Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period		249		354	249		558
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		246		206	972		923
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		16		45	125		51
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	16		41
Nonaccruing Financing Receivable Modifications [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period		1,154		481	1,412		795
Nonaccruing Financing Receivable Modifications [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period		$ 590		$ 735	$ 1,157		$ 1,012

[1] 1) Includes $2.1 million of loans past due 90 days or more and accruing. The remaining loans were past due nonaccrual loans.(2) Includes $50.1 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.