Loans and Leases - Age Analysis of Past Due Loans and Leases (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	$ 4,457,089	$ 4,400,497
Accruing loans and leases	5,369,910	5,276,807
Nonaccrual loans and lease	30,876	33,210
Loans and leases held for investment	5,400,786	5,310,017	$ 5,415,006
Financial Asset, 30 to 59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	9,451	9,036
Financial Asset, 60 to 89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	247	1,609
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	274	498
Financial Asset Not Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	9,972	11,143
Financial Asset Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	5,359,938	5,265,664
Commercial Financial And Agricultural [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	932,485	956,396
Accruing loans and leases	932,037	955,948
Nonaccrual loans and lease	448	448
Loans and leases held for investment	932,485	956,396	871,996
Commercial Financial And Agricultural [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	4,880	3,407
Commercial Financial And Agricultural [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	0	894
Commercial Financial And Agricultural [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	0	0
Commercial Financial And Agricultural [Member] | Financial Asset Not Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	4,880	4,301
Commercial Financial And Agricultural [Member] | Financial Asset Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	927,157	951,647
Paycheck Protection Program Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	10,298	31,748
Accruing loans and leases	10,298	31,748
Nonaccrual loans and lease	0	0
Loans and leases held for investment	10,298	31,748	528,452
Paycheck Protection Program Loans | Financial Asset, 30 to 59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	0	367
Paycheck Protection Program Loans | Financial Asset, 60 to 89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	0	0
Paycheck Protection Program Loans | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	0	0
Paycheck Protection Program Loans | Financial Asset Not Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	0	367
Paycheck Protection Program Loans | Financial Asset Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	10,298	31,381
Real-Estate Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	2,816,737	2,718,535
Accruing loans and leases	2,790,326	2,690,635
Nonaccrual loans and lease	26,411	27,900
Loans and leases held for investment	2,816,737	2,718,535	2,531,700
Real-Estate Commercial [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	2,833	234
Real-Estate Commercial [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	0	0
Real-Estate Commercial [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	0	0
Real-Estate Commercial [Member] | Financial Asset Not Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	2,833	234
Real-Estate Commercial [Member] | Financial Asset Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	2,787,493	2,690,401
Real-Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	285,083	283,918
Accruing loans and leases	285,083	283,918
Nonaccrual loans and lease	0	0
Loans and leases held for investment	285,083	283,918	249,652
Real-Estate Construction [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	0	0
Real-Estate Construction [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	0	0
Real-Estate Construction [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	0	0
Real-Estate Construction [Member] | Financial Asset Not Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	0	0
Real-Estate Construction [Member] | Financial Asset Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	285,083	283,918
Real Estate Residential Secured For Business Purpose [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	412,486	409,900
Accruing loans and leases	411,366	407,713
Nonaccrual loans and lease	1,120	2,187
Loans and leases held for investment	412,486	409,900	387,801
Real Estate Residential Secured For Business Purpose [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	294	542
Real Estate Residential Secured For Business Purpose [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	89	0
Real Estate Residential Secured For Business Purpose [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	0	216
Real Estate Residential Secured For Business Purpose [Member] | Financial Asset Not Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	383	758
Real Estate Residential Secured For Business Purpose [Member] | Financial Asset Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	410,983	406,955
Real Estate-Residential Secured For Personal Purpose [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	568,735	540,566
Accruing loans and leases	566,476	538,517
Nonaccrual loans and lease	2,259	2,049
Loans and leases held for investment	568,735	540,566	494,349
Real Estate-Residential Secured For Personal Purpose [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	1,112	2,976
Real Estate-Residential Secured For Personal Purpose [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	0	162
Real Estate-Residential Secured For Personal Purpose [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	0	0
Real Estate-Residential Secured For Personal Purpose [Member] | Financial Asset Not Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	1,112	3,138
Real Estate-Residential Secured For Personal Purpose [Member] | Financial Asset Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	565,364	535,379
Real Estate Home Equity Secured For Personal Purpose [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	160,134	158,909
Accruing loans and leases	159,645	158,364
Nonaccrual loans and lease	489	545
Loans and leases held for investment	160,134	158,909	162,529
Real Estate Home Equity Secured For Personal Purpose [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	77	646
Real Estate Home Equity Secured For Personal Purpose [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	20	129
Real Estate Home Equity Secured For Personal Purpose [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	0	0
Real Estate Home Equity Secured For Personal Purpose [Member] | Financial Asset Not Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	97	775
Real Estate Home Equity Secured For Personal Purpose [Member] | Financial Asset Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	159,548	157,589
Loans to Individuals [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	26,249	25,504
Accruing loans and leases	26,249	25,504
Nonaccrual loans and lease	0	0
Loans and leases held for investment	26,249	25,504	25,468
Loans to Individuals [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	34	90
Loans to Individuals [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	14	27
Loans to Individuals [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	185	180
Loans to Individuals [Member] | Financial Asset Not Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	233	297
Loans to Individuals [Member] | Financial Asset Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	26,016	25,207
Lease Financings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	188,579	184,541
Accruing loans and leases	188,430	184,460
Nonaccrual loans and lease	149	81
Loans and leases held for investment	188,579	184,541	$ 163,059
Lease Financings [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	221	774
Lease Financings [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	124	397
Lease Financings [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	89	102
Lease Financings [Member] | Financial Asset Not Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	434	1,273
Lease Financings [Member] | Financial Asset Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	$ 187,996	$ 183,187