Loans, Troubled Debt Restructuring with subsequent default (Details)	12 Months Ended
	Dec. 31, 2020 USD ($) contracts	Dec. 31, 2019 USD ($) contracts	Dec. 31, 2018 USD ($) contracts
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructuring, Subsequent Default, Number of Contracts | contracts	55	70	73
Financing Receivable, Troubled Debt Restructuring, Subsequent Default	$ 4,401,000	$ 1,365,000	$ 1,319,000
Nonaccruing Financing Receivable Modifications [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructuring, Subsequent Default	3,700,000	1,000,000.0	1,200,000
Accruing Financing Receivable Modifications [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructuring, Subsequent Default	$ 706,000	$ 350,000	$ 86,000
Commercial Financial And Agricultural [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructuring, Subsequent Default, Number of Contracts | contracts	4	1	3
Financing Receivable, Troubled Debt Restructuring, Subsequent Default	$ 2,776,000	$ 20,000	$ 104,000
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructuring, Subsequent Default, Number of Contracts | contracts	1	0	0
Financing Receivable, Troubled Debt Restructuring, Subsequent Default	$ 223,000
Construction Real Estate Remaining Commercial [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructuring, Subsequent Default, Number of Contracts | contracts	0	0	0
Construction Real Estate Mortgage [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructuring, Subsequent Default, Number of Contracts | contracts	0	0	0
Financing Receivable, Troubled Debt Restructuring, Subsequent Default	$ 0
Construction Real Estate Installment [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructuring, Subsequent Default, Number of Contracts | contracts	1	0	0
Financing Receivable, Troubled Debt Restructuring, Subsequent Default	$ 14,000
Residential Real Estate Commercial [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructuring, Subsequent Default, Number of Contracts | contracts	1	0	0
Financing Receivable, Troubled Debt Restructuring, Subsequent Default	$ 3,000
Residential Real Estate Mortgage [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructuring, Subsequent Default, Number of Contracts | contracts	11	7	8
Financing Receivable, Troubled Debt Restructuring, Subsequent Default	$ 993,000	$ 665,000	$ 518,000
Residential Real Estate Home Equity Line Of Credit [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructuring, Subsequent Default, Number of Contracts | contracts	0	6	2
Financing Receivable, Troubled Debt Restructuring, Subsequent Default		$ 141,000	$ 32,000
Residential Real Estate Installment [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructuring, Subsequent Default, Number of Contracts | contracts	3	0	1
Financing Receivable, Troubled Debt Restructuring, Subsequent Default	$ 32,000		$ 29,000
Consumer Loan [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructuring, Subsequent Default, Number of Contracts | contracts	34	56	59
Financing Receivable, Troubled Debt Restructuring, Subsequent Default	$ 360,000	$ 539,000	$ 636,000
Leases
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructuring, Subsequent Default, Number of Contracts | contracts	0	0	0
Financing Receivable, Troubled Debt Restructuring, Subsequent Default	$ 0