Loans, Allowance for Credit Losses, and Asset Quality Information - Accrued Interest Receivable Written Off (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Financing Receivable, Allowance for Credit Loss [Line Items]
Accrued interest receivable written off	$ 132	$ 293	$ 699
Commercial, financial, and agricultural
Financing Receivable, Allowance for Credit Loss [Line Items]
Accrued interest receivable written off	8	64	195
Real estate, commercial | Real estate – construction, land development & other land loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Accrued interest receivable written off	12	0	6
Real estate, commercial | Real estate – mortgage – commercial and other
Financing Receivable, Allowance for Credit Loss [Line Items]
Accrued interest receivable written off	100	220	453
Real estate, mortgage | Real estate – mortgage – residential (1-4 family) first mortgages
Financing Receivable, Allowance for Credit Loss [Line Items]
Accrued interest receivable written off	10	5	31
Real estate, mortgage | Real estate – mortgage – home equity loans / lines of credit
Financing Receivable, Allowance for Credit Loss [Line Items]
Accrued interest receivable written off	2	4	14
Consumer loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Accrued interest receivable written off	$ 0	$ 0	$ 0