Loans Schedule of loans individually and collectively evaluated for impairment (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Impaired [Line Items]
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans	$ 111,378	$ 83,176
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans, Individually Evaluated for Impairment	77,491	48,144
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans, Collectively Evaluated for Impairment	33,887	35,032
Commercial Financial And Agricultural [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans	33,125	15,194
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans, Individually Evaluated for Impairment	33,088	15,120
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans, Collectively Evaluated for Impairment	37	74
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans	41,791	28,426
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans, Individually Evaluated for Impairment	41,791	28,426
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	453	1,866
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans, Individually Evaluated for Impairment	453	1,866
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	109	15
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	109	15
Construction Real Estate Installment [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans	77	28
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	77	28
Residential Real Estate Commercial [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans	2,025	2,732
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans, Individually Evaluated for Impairment	2,025	2,732
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	24,097	25,992
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	24,097	25,992
Residential Real Estate Home Equity Line Of Credit [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans	3,072	3,186
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	3,072	3,186
Residential Real Estate Installment [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans	2,426	1,517
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	2,426	1,517
Consumer Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans	4,069	4,220
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	4,069	4,220
Leases
Financing Receivable, Impaired [Line Items]
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans	134	0
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans, Individually Evaluated for Impairment	134	0
Financing Receivable Recorded Investment Nonaccrual And Accruing Restructured Loans, Collectively Evaluated for Impairment	$ 0	$ 0