Loans Schedule of loans individually and collectively evaluated for impairment (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Impaired [Line Items]
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans	$ 138,256	$ 111,378
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans, Individually Evaluated for Impairment	108,455	77,491
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans, Collectively Evaluated for Impairment	29,801	33,887
Commercial Financial And Agricultural [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans	28,880	33,125
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans, Individually Evaluated for Impairment	28,836	33,088
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans, Collectively Evaluated for Impairment	44	37
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans	70,357	41,791
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans, Individually Evaluated for Impairment	70,357	41,791
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans, Collectively Evaluated for Impairment	0	0
Construction Real Estate Remaining Commercial [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans	3,110	453
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans, Individually Evaluated for Impairment	3,110	453
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans, Collectively Evaluated for Impairment	0	0
Construction Real Estate Mortgage [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans	30	109
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans, Individually Evaluated for Impairment	0	0
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans, Collectively Evaluated for Impairment	30	109
Construction Real Estate Installment [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans	15	77
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans, Individually Evaluated for Impairment	0	0
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans, Collectively Evaluated for Impairment	15	77
Residential Real Estate Commercial [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans	4,557	2,025
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans, Individually Evaluated for Impairment	4,557	2,025
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans, Collectively Evaluated for Impairment	0	0
Residential Real Estate Mortgage [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans	22,416	24,097
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans, Individually Evaluated for Impairment	0	0
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans, Collectively Evaluated for Impairment	22,416	24,097
Residential Real Estate Home Equity Line Of Credit [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans	2,195	3,072
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans, Individually Evaluated for Impairment	0	0
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans, Collectively Evaluated for Impairment	2,195	3,072
Residential Real Estate Installment [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans	1,912	2,426
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans, Individually Evaluated for Impairment	0	0
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans, Collectively Evaluated for Impairment	1,912	2,426
Consumer Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans	3,189	4,069
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans, Individually Evaluated for Impairment	0	0
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans, Collectively Evaluated for Impairment	3,189	4,069
Leases
Financing Receivable, Impaired [Line Items]
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans	1,595	134
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans, Individually Evaluated for Impairment	1,595	134
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans, Collectively Evaluated for Impairment	$ 0	$ 0