Loans Schedule of troubled debt restructurings on financing receivables (Details)	12 Months Ended
	Dec. 31, 2020 USD ($) contracts	Dec. 31, 2019 USD ($) contracts	Dec. 31, 2018 USD ($) contracts
Financing Receivable, Impaired [Line Items]
Troubled Debt Restructuring, Classification removed	$ 2,300,000	$ 38,000
TDRs included in nonaccrual loan totals	25,800,000	34,300,000
Nonaccrual TDRs considered current	12,900,000	23,200,000
TDRs included in accruing loan totals	20,900,000	21,300,000
Loans and Leases Receivable, Impaired, Commitment to Lend	6,700,000	7,900,000
Specific Reserves Related To Troubled Debt Restructuring	200,000	2,200,000
Additional specific reserves related to troubled debt restructuring	7,000	1,300	$ 200,000
Modified substandard commercial loans, total recorded investment	200,000	600,000
Modified substandard consumer loans total recorded investment	57,900,000	36,200,000
Nonaccrual loans not classified as TDRs at prior fiscal year end	$ 400,000	$ 2,100,000	$ 500,000
Financing Receivable, Modifications, Number of Contracts | contracts	292	443	392
Total Recorded Investment Modified as TDRs During Period	$ 10,346,000	$ 26,673,000	$ 9,191,000
Accruing Financing Receivable Modifications [Member]
Financing Receivable, Impaired [Line Items]
Total Recorded Investment Modified as TDRs During Period	1,569,000	8,465,000	2,569,000
Nonaccruing Financing Receivable Modifications [Member]
Financing Receivable, Impaired [Line Items]
Total Recorded Investment Modified as TDRs During Period	$ 8,777,000	$ 18,208,000	$ 6,622,000
Commercial Financial And Agricultural [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Modifications, Number of Contracts | contracts	12	30	21
Total Recorded Investment Modified as TDRs During Period	$ 3,813,000	$ 13,861,000	$ 857,000
Commercial Financial And Agricultural [Member] | Accruing Financing Receivable Modifications [Member]
Financing Receivable, Impaired [Line Items]
Total Recorded Investment Modified as TDRs During Period	107,000	6,040,000	28,000
Commercial Financial And Agricultural [Member] | Nonaccruing Financing Receivable Modifications [Member]
Financing Receivable, Impaired [Line Items]
Total Recorded Investment Modified as TDRs During Period	$ 3,706,000	$ 7,821,000	$ 829,000
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Modifications, Number of Contracts | contracts	9	8	17
Total Recorded Investment Modified as TDRs During Period	$ 3,235,000	$ 8,270,000	$ 3,586,000
Commercial Real Estate Portfolio Segment [Member] | Accruing Financing Receivable Modifications [Member]
Financing Receivable, Impaired [Line Items]
Total Recorded Investment Modified as TDRs During Period		415,000	414,000
Commercial Real Estate Portfolio Segment [Member] | Nonaccruing Financing Receivable Modifications [Member]
Financing Receivable, Impaired [Line Items]
Total Recorded Investment Modified as TDRs During Period	$ 3,235,000	$ 7,855,000	$ 3,172,000
Construction Real Estate Remaining Commercial [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Modifications, Number of Contracts | contracts	0	3	1
Total Recorded Investment Modified as TDRs During Period		$ 415,000
Construction Real Estate Remaining Commercial [Member] | Nonaccruing Financing Receivable Modifications [Member]
Financing Receivable, Impaired [Line Items]
Total Recorded Investment Modified as TDRs During Period		$ 415,000
Construction Real Estate Mortgage [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Modifications, Number of Contracts | contracts	1	2	0
Total Recorded Investment Modified as TDRs During Period	$ 26,000	$ 77,000
Construction Real Estate Mortgage [Member] | Accruing Financing Receivable Modifications [Member]
Financing Receivable, Impaired [Line Items]
Total Recorded Investment Modified as TDRs During Period	$ 26,000	$ 77,000	$ 0
Construction Real Estate Installment [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Modifications, Number of Contracts | contracts	1	0	2
Total Recorded Investment Modified as TDRs During Period	$ 14,000		$ 10,000
Construction Real Estate Installment [Member] | Accruing Financing Receivable Modifications [Member]
Financing Receivable, Impaired [Line Items]
Total Recorded Investment Modified as TDRs During Period	0	$ 0	$ 10,000
Construction Real Estate Installment [Member] | Nonaccruing Financing Receivable Modifications [Member]
Financing Receivable, Impaired [Line Items]
Total Recorded Investment Modified as TDRs During Period	$ 14,000
Residential Real Estate Commercial [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Modifications, Number of Contracts | contracts	3	3	3
Total Recorded Investment Modified as TDRs During Period	$ 156,000	$ 100,000	$ 417,000
Residential Real Estate Commercial [Member] | Accruing Financing Receivable Modifications [Member]
Financing Receivable, Impaired [Line Items]
Total Recorded Investment Modified as TDRs During Period	153,000		54,000
Residential Real Estate Commercial [Member] | Nonaccruing Financing Receivable Modifications [Member]
Financing Receivable, Impaired [Line Items]
Total Recorded Investment Modified as TDRs During Period	$ 3,000	$ 100,000	$ 363,000
Residential Real Estate Mortgage [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Modifications, Number of Contracts | contracts	27	21	25
Total Recorded Investment Modified as TDRs During Period	$ 1,956,000	$ 1,124,000	$ 1,696,000
Residential Real Estate Mortgage [Member] | Accruing Financing Receivable Modifications [Member]
Financing Receivable, Impaired [Line Items]
Total Recorded Investment Modified as TDRs During Period	888,000	535,000	842,000
Residential Real Estate Mortgage [Member] | Nonaccruing Financing Receivable Modifications [Member]
Financing Receivable, Impaired [Line Items]
Total Recorded Investment Modified as TDRs During Period	$ 1,068,000	$ 589,000	$ 854,000
Residential Real Estate Home Equity Line Of Credit [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Modifications, Number of Contracts | contracts	7	18	21
Total Recorded Investment Modified as TDRs During Period	$ 66,000	$ 360,000	$ 644,000
Residential Real Estate Home Equity Line Of Credit [Member] | Accruing Financing Receivable Modifications [Member]
Financing Receivable, Impaired [Line Items]
Total Recorded Investment Modified as TDRs During Period	14,000	126,000	558,000
Residential Real Estate Home Equity Line Of Credit [Member] | Nonaccruing Financing Receivable Modifications [Member]
Financing Receivable, Impaired [Line Items]
Total Recorded Investment Modified as TDRs During Period	$ 52,000	$ 234,000	$ 86,000
Residential Real Estate Installment [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Modifications, Number of Contracts | contracts	18	34	19
Total Recorded Investment Modified as TDRs During Period	$ 228,000	$ 1,075,000	$ 528,000
Residential Real Estate Installment [Member] | Accruing Financing Receivable Modifications [Member]
Financing Receivable, Impaired [Line Items]
Total Recorded Investment Modified as TDRs During Period	163,000	1,047,000	459,000
Residential Real Estate Installment [Member] | Nonaccruing Financing Receivable Modifications [Member]
Financing Receivable, Impaired [Line Items]
Total Recorded Investment Modified as TDRs During Period	$ 65,000	$ 28,000	$ 69,000
Consumer Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Modifications, Number of Contracts | contracts	214	324	283
Total Recorded Investment Modified as TDRs During Period	$ 852,000	$ 1,391,000	$ 1,453,000
Consumer Portfolio Segment [Member] | Accruing Financing Receivable Modifications [Member]
Financing Receivable, Impaired [Line Items]
Total Recorded Investment Modified as TDRs During Period	218,000	225,000	204,000
Consumer Portfolio Segment [Member] | Nonaccruing Financing Receivable Modifications [Member]
Financing Receivable, Impaired [Line Items]
Total Recorded Investment Modified as TDRs During Period	$ 634,000	$ 1,166,000	$ 1,249,000