Loans and Leases - Non-Performing Loans and Leases (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Non-Performing Loans and Leases [Line Items]
Nonaccrual loans and leases	$ 38,578	$ 26,208
Accruing troubled debt restructured loans and lease modifications	54	542
Loans and leases 90 days or more past due and accruing interest	143	192
Total Nonperforming Loans and Leases	38,775	26,942
Nonaccrual troubled debt restructured loans and lease modifications	13,800	1,300
Commercial, Financial and Agricultural [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual loans and leases	3,442	3,365
Accruing troubled debt restructured loans and lease modifications	0	382
Loans and leases 90 days or more past due and accruing interest	20	0
Total Nonperforming Loans and Leases	3,462	3,747
Real Estate-Commercial [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual loans and leases	27,928	18,214
Accruing troubled debt restructured loans and lease modifications	0	0
Loans and leases 90 days or more past due and accruing interest	0	0
Total Nonperforming Loans and Leases	27,928	18,214
Real Estate-Construction [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual loans and leases	257	106
Accruing troubled debt restructured loans and lease modifications	0	0
Loans and leases 90 days or more past due and accruing interest	0	0
Total Nonperforming Loans and Leases	257	106
Real Estate-Residential Secured for Business Purpose [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual loans and leases	2,980	1,318
Accruing troubled debt restructured loans and lease modifications	0	160
Loans and leases 90 days or more past due and accruing interest	0	0
Total Nonperforming Loans and Leases	2,980	1,478
Real Estate-Residential Secured for Personal Purpose [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual loans and leases	2,038	1,587
Accruing troubled debt restructured loans and lease modifications	0	0
Loans and leases 90 days or more past due and accruing interest	0	0
Total Nonperforming Loans and Leases	2,038	1,587
Real Estate-Home Equity Secured for Personal Purpose [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual loans and leases	1,427	1,448
Accruing troubled debt restructured loans and lease modifications	54	0
Loans and leases 90 days or more past due and accruing interest	0	0
Total Nonperforming Loans and Leases	1,481	1,448
Loans to Individuals [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual loans and leases	0	0
Accruing troubled debt restructured loans and lease modifications	0	0
Loans and leases 90 days or more past due and accruing interest	74	55
Total Nonperforming Loans and Leases	74	55
Lease Financings [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual loans and leases	506	170
Accruing troubled debt restructured loans and lease modifications	0	0
Loans and leases 90 days or more past due and accruing interest	49	137
Total Nonperforming Loans and Leases	$ 555	$ 307