Loans and Leases - Age Analysis of Past Due Loans and Leases (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	$ 4,400,497	$ 4,460,111
Accruing loans and leases	5,276,807	5,275,149
Nonaccrual loans and leases	33,210	31,692
Loans and leases held for investment	5,310,017	5,306,841
Financial Asset, 30 to 59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	9,036	16,173
Financial Asset, 60 to 89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	1,609	2,218
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	498	1,392
Financial Asset, Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	11,143	19,783
Financial Asset, Not Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	5,265,664	5,255,366
Commercial, Financial and Agricultural [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	956,396	892,665
Accruing loans and leases	955,948	889,838
Nonaccrual loans and leases	448	2,827
Loans and leases held for investment	956,396	892,665
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	3,407	1,104
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	894	279
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	50
Commercial, Financial and Agricultural [Member] | Financial Asset, Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	4,301	1,433
Commercial, Financial and Agricultural [Member] | Financial Asset, Not Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	951,647	888,405
Paycheck Protection Program Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	31,748	483,773
Accruing loans and leases	31,748	483,773
Nonaccrual loans and leases	0	0
Loans and leases held for investment	31,748	483,773
Paycheck Protection Program Loans [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	367	0
Paycheck Protection Program Loans [Member] | 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 [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
Paycheck Protection Program Loans [Member] | Financial Asset, Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	367	0
Paycheck Protection Program Loans [Member] | Financial Asset, Not Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	31,381	483,773
Real Estate-Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	2,718,535	2,458,872
Accruing loans and leases	2,690,635	2,436,133
Nonaccrual loans and leases	27,900	22,739
Loans and leases held for investment	2,718,535	2,458,872
Real Estate-Commercial [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	234	3,230
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	859
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	945
Real Estate-Commercial [Member] | Financial Asset, Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	234	5,034
Real Estate-Commercial [Member] | Financial Asset, Not Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	2,690,401	2,431,099
Real Estate-Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	283,918	243,355
Accruing loans and leases	283,918	243,355
Nonaccrual loans and leases	0	0
Loans and leases held for investment	283,918	243,355
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	361
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, Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	0	361
Real Estate-Construction [Member] | Financial Asset, Not Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	283,918	242,994
Real Estate-Residential Secured for Business Purpose [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	409,900	381,446
Accruing loans and leases	407,713	378,660
Nonaccrual loans and leases	2,187	2,786
Loans and leases held for investment	409,900	381,446
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	542	3,726
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	0	603
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	216	0
Real Estate-Residential Secured for Business Purpose [Member] | Financial Asset, Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	758	4,329
Real Estate-Residential Secured for Business Purpose [Member] | Financial Asset, Not Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	406,955	374,331
Real Estate-Residential Secured for Personal Purpose [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	540,566	487,600
Accruing loans and leases	538,517	485,514
Nonaccrual loans and leases	2,049	2,086
Loans and leases held for investment	540,566	487,600
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	2,976	6,057
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	162	80
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, Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	3,138	6,137
Real Estate-Residential Secured for Personal Purpose [Member] | Financial Asset, Not Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	535,379	479,377
Real Estate-Home Equity Secured for Personal Purpose [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	158,909	166,609
Accruing loans and leases	158,364	165,562
Nonaccrual loans and leases	545	1,047
Loans and leases held for investment	158,909	166,609
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	646	607
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	129	32
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, Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	775	639
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	157,589	164,923
Loans to Individuals [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	25,504	27,482
Accruing loans and leases	25,504	27,482
Nonaccrual loans and leases	0	0
Loans and leases held for investment	25,504	27,482
Loans to Individuals [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	90	190
Loans to Individuals [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	27	74
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	180	185
Loans to Individuals [Member] | Financial Asset, Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	297	449
Loans to Individuals [Member] | Financial Asset, Not Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	25,207	27,033
Lease Financings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	184,541	165,039
Accruing loans and leases	184,460	164,832
Nonaccrual loans and leases	81	207
Loans and leases held for investment	184,541	165,039
Lease Financings [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	774	898
Lease Financings [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	397	291
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	102	212
Lease Financings [Member] | Financial Asset, Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	1,273	1,401
Lease Financings [Member] | Financial Asset, Not Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivables, gross	$ 183,187	$ 163,431