Allowance For Loan Losses (Activity In The Allowance For Loan Losses) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan and Lease Losses, Reserve Estimate Methodology, Historical Loss Period Factor					96 months	84 months
Financing Receivable, Allowance for Credit Losses, Write-downs	$ 3,474	$ 4,377	$ 9,640	$ 11,131
Financing Receivable, Allowance for Credit Losses, Recovery	1,328	2,504	5,312	6,999
Financing Receivables Allowance For Credit Losses Net Charge Offs	2,146	1,873	4,328	4,132
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	49,452	53,822	49,988	50,624	$ 50,624
Ending balance	50,246	55,232	50,246	55,232	49,988	$ 50,624
Provision for Loan, Lease, and Other Losses	2,940	3,283	4,586	8,740
Commercial Financial And Agricultural [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Allowance for Credit Losses, Write-downs	993	626	1,929	1,283
Financing Receivable, Allowance for Credit Losses, Recovery	136	115	994	647
Financing Receivables Allowance For Credit Losses Net Charge Offs	857	511	935	636
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	14,478	16,746	15,022	13,434	13,434
Ending balance	15,015	17,977	15,015	17,977	15,022	13,434
Provision for Loan, Lease, and Other Losses	1,394	1,742	928	5,179
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Allowance for Credit Losses, Write-downs	23	628	252	1,050
Financing Receivable, Allowance for Credit Losses, Recovery	27	13	203	368
Financing Receivables Allowance For Credit Losses Net Charge Offs	(4)	615	49	682
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	9,406	10,451	9,601	10,432	10,432
Ending balance	9,747	10,172	9,747	10,172	9,601	10,432
Provision for Loan, Lease, and Other Losses	337	336	195	422
Construction Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Allowance for Credit Losses, Write-downs	26	78	57	105
Financing Receivable, Allowance for Credit Losses, Recovery	156	303	435	686
Financing Receivables Allowance For Credit Losses Net Charge Offs	(130)	(225)	(378)	(581)
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	4,652	4,677	4,430	5,247	5,247
Ending balance	4,595	5,401	4,595	5,401	4,430	5,247
Provision for Loan, Lease, and Other Losses	(187)	499	(213)	(427)
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Allowance for Credit Losses, Write-downs	61	217	279	987
Financing Receivable, Allowance for Credit Losses, Recovery	130	1,061	734	1,688
Financing Receivables Allowance For Credit Losses Net Charge Offs	(69)	(844)	(455)	(701)
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	9,245	10,319	9,321	10,958	10,958
Ending balance	9,102	10,085	9,102	10,085	9,321	10,958
Provision for Loan, Lease, and Other Losses	(212)	(1,078)	(674)	(1,574)
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Allowance for Credit Losses, Write-downs	2,371	2,828	7,123	7,706
Financing Receivable, Allowance for Credit Losses, Recovery	875	1,011	2,942	3,609
Financing Receivables Allowance For Credit Losses Net Charge Offs	1,496	1,817	4,181	4,097
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	11,671	11,629	11,614	10,553	10,553
Ending balance	11,787	11,597	11,787	11,597	11,614	10,553
Provision for Loan, Lease, and Other Losses	1,612	1,785	4,354	5,141
Leases [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Allowance for Credit Losses, Write-downs	0	0	0	0
Financing Receivable, Allowance for Credit Losses, Recovery	4	1	4	1
Financing Receivables Allowance For Credit Losses Net Charge Offs	(4)	(1)	(4)	(1)
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	0	0	0	0	0
Ending balance	0	0	0	0	$ 0	$ 0
Provision for Loan, Lease, and Other Losses	$ (4)	$ (1)	$ (4)	$ (1)