Loans (Aging Of Recorded Investment In Past Due Loans) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019		Mar. 31, 2018	Dec. 31, 2018
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing loans past due 30-89 days		$ 18,757			$ 29,919
Past due nonaccrual loans and loans past due 90 days or more and accruing		20,955	[1]		19,602	[2]
Total loans past due		39,712			49,521
Total current		5,720,621			5,660,277
Recorded Investment		5,760,333			5,709,798
Loans past due 90 days or more and accruing		1,589			2,302
Impaired Financing Receivable, Recorded Investment, Nonaccrual loans which are current in regards to contractual P&I payments		49,800			50,700
Financing Receivable, Modifications, Recorded Investment, During Period		4,560		$ 1,835
Construction Real Estate Commercial [Domain]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing loans past due 30-89 days		368
Past due nonaccrual loans and loans past due 90 days or more and accruing		2,299	[1]		1,635	[2]
Total loans past due		2,667			1,635
Total current		166,973			174,466
Recorded Investment		169,640			176,101
Loans past due 90 days or more and accruing		0			0
Financing Receivable, Modifications, Recorded Investment, During Period		480		63
Commercial Financial And Agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing loans past due 30-89 days		1,428			4,786
Past due nonaccrual loans and loans past due 90 days or more and accruing		2,290	[1]		1,375	[2]
Total loans past due		3,718			6,161
Total current		1,088,546			1,071,228
Loans past due 90 days or more and accruing		45			10
Financing Receivable, Modifications, Recorded Investment, During Period		472		55
Construction Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing loans past due 30-89 days		254			133
Past due nonaccrual loans and loans past due 90 days or more and accruing		80	[1]		20	[2]
Total loans past due		334			153
Total current		71,710			70,539
Recorded Investment		72,044			70,692
Loans past due 90 days or more and accruing		80			20
Construction Real Estate - Installment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing loans past due 30-89 days		18			28
Past due nonaccrual loans and loans past due 90 days or more and accruing		11	[1]		19	[2]
Total loans past due		29			47
Total current		2,305			2,393
Recorded Investment		2,334			2,440
Loans past due 90 days or more and accruing		0			0
Residential Real Estate Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing loans past due 30-89 days		124			683
Past due nonaccrual loans and loans past due 90 days or more and accruing		873	[1]		1,104	[2]
Total loans past due		997			1,787
Total current		429,943			429,093
Recorded Investment		430,940			430,880
Loans past due 90 days or more and accruing		0
Residential Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing loans past due 30-89 days		9,913			13,210
Past due nonaccrual loans and loans past due 90 days or more and accruing		8,524	[1]		8,553	[2]
Total loans past due		18,437			21,763
Total current		1,111,350			1,113,742
Recorded Investment		1,129,787			1,135,505
Loans past due 90 days or more and accruing		582			1,124
Financing Receivable, Modifications, Recorded Investment, During Period		564		650
Residential Real Estate - HELOC [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing loans past due 30-89 days		462			620
Past due nonaccrual loans and loans past due 90 days or more and accruing		975	[1]		907	[2]
Total loans past due		1,437			1,527
Total current		208,066			214,915
Recorded Investment		209,503			216,442
Loans past due 90 days or more and accruing		155			9
Financing Receivable, Modifications, Recorded Investment, During Period		81		339
Residential Real Estate - Installment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing loans past due 30-89 days		98			155
Past due nonaccrual loans and loans past due 90 days or more and accruing		338	[1]		274	[2]
Total loans past due		436			429
Total current		13,238			13,934
Recorded Investment		13,674			14,363
Loans past due 90 days or more and accruing		0			24
Financing Receivable, Modifications, Recorded Investment, During Period		189		115
Commercial Financial And Agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment	[3]	1,092,264			1,077,389
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing loans past due 30-89 days		57			780
Past due nonaccrual loans and loans past due 90 days or more and accruing		3,886	[1]		3,584	[2]
Total loans past due		3,943			4,364
Total current		1,327,780			1,283,431
Recorded Investment	[3]	1,331,723			1,287,795
Loans past due 90 days or more and accruing		0
Financing Receivable, Modifications, Recorded Investment, During Period		2,215		249
Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing loans past due 30-89 days		6,035			9,524
Past due nonaccrual loans and loans past due 90 days or more and accruing		1,679	[1]		2,131	[2]
Total loans past due		7,714			11,655
Total current		1,298,569			1,284,237
Recorded Investment		1,306,283			1,295,892
Loans past due 90 days or more and accruing		727			1,115
Financing Receivable, Modifications, Recorded Investment, During Period		559		364
Leases [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accruing loans past due 30-89 days		0			0
Past due nonaccrual loans and loans past due 90 days or more and accruing		0	[1]		0	[2]
Total loans past due		0			0
Total current		2,141			2,299
Recorded Investment		2,141			$ 2,299
Accruing Financing Receivable Modifications [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period		652		429
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		480		63
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
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
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		54		0
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		0		251
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		94		102
Accruing Financing Receivable Modifications [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period		24		13
Nonaccruing Financing Receivable Modifications [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period		3,908		1,406
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		472		55
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		510		650
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		81		88
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		95		13
Nonaccruing Financing Receivable Modifications [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period		2,215		249
Nonaccruing Financing Receivable Modifications [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Modifications, Recorded Investment, During Period		$ 535		$ 351

[1] 1) Includes an aggregate of $1.6 million of loans past due 90 days or more and accruing. The remaining loans were past due nonaccrual loans.(2) Includes an aggregate off $49.8 million of nonaccrual loans which were current in regards to contractual principal and interest payments

[2] 1) Includes an aggregate of $2.3 million of loans past due 90 days or more and accruing. The remaining loans were past due nonaccrual loans.(2) Includes an aggregate of $50.7 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.