Loans and Leases - Nonperforming Loans and Leases (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Nonperforming Loans And Leases [Line Items]
Total nonaccrual loans and lease	$ 30,019	$ 38,578
Accruing troubled debt restructured loans and lease modifications	53	54
Loans and lease 90 days or more past due and accruing interest	3,573	143
Total nonperforming loans and leases	33,645	38,775
Nonaccrual troubled debt restructured loans and lease modifications	14,200	13,800
Commercial Financial And Agricultural [Member]
Nonperforming Loans And Leases [Line Items]
Total nonaccrual loans and lease	3,809	3,442
Accruing troubled debt restructured loans and lease modifications	0	0
Loans and lease 90 days or more past due and accruing interest	27	20
Total nonperforming loans and leases	3,836	3,462
Real-Estate Commercial [Member]
Nonperforming Loans And Leases [Line Items]
Total nonaccrual loans and lease	20,464	27,928
Accruing troubled debt restructured loans and lease modifications	0	0
Loans and lease 90 days or more past due and accruing interest	1,539	0
Total nonperforming loans and leases	22,003	27,928
Real-Estate Construction [Member]
Nonperforming Loans And Leases [Line Items]
Total nonaccrual loans and lease	0	257
Accruing troubled debt restructured loans and lease modifications	0	0
Loans and lease 90 days or more past due and accruing interest	0	0
Total nonperforming loans and leases	0	257
Real Estate Residential Secured For Business Purpose [Member]
Nonperforming Loans And Leases [Line Items]
Total nonaccrual loans and lease	2,151	2,980
Accruing troubled debt restructured loans and lease modifications	0	0
Loans and lease 90 days or more past due and accruing interest	1,027	0
Total nonperforming loans and leases	3,178	2,980
Real Estate-Residential Secured For Personal Purpose [Member]
Nonperforming Loans And Leases [Line Items]
Total nonaccrual loans and lease	2,395	2,038
Accruing troubled debt restructured loans and lease modifications	0	0
Loans and lease 90 days or more past due and accruing interest	228	0
Total nonperforming loans and leases	2,623	2,038
Real Estate Home Equity Secured For Personal Purpose [Member]
Nonperforming Loans And Leases [Line Items]
Total nonaccrual loans and lease	948	1,427
Accruing troubled debt restructured loans and lease modifications	53	54
Loans and lease 90 days or more past due and accruing interest	0	0
Total nonperforming loans and leases	1,001	1,481
Loans to Individuals [Member]
Nonperforming Loans And Leases [Line Items]
Total nonaccrual loans and lease	0	0
Accruing troubled debt restructured loans and lease modifications	0	0
Loans and lease 90 days or more past due and accruing interest	23	74
Total nonperforming loans and leases	23	74
Lease Financings [Member]
Nonperforming Loans And Leases [Line Items]
Total nonaccrual loans and lease	252	506
Accruing troubled debt restructured loans and lease modifications	0	0
Loans and lease 90 days or more past due and accruing interest	729	49
Total nonperforming loans and leases	$ 981	$ 555