Loans and Allowance for Credit Losses - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non Accrual Status Of Loans After Number Of Days Past Due	90 days
Default Status Of TDRs After Number Of Days Past Due	90 days
Charge-offs	$ 1,883,000	$ 1,623,000
Unfunded commitments related to nonperforming loans	200,000		$ 200,000
Off balance sheet reserve to nonperforming loans	0		0
Total gains or losses included in earnings	0	0
Recorded investment	44,234,000		35,487,000
Loans with modifications to rate and payment due to reamortization		10,000
Loans and Leases Receivable, Gross	8,656,945,000		7,642,143,000
Loans and Leases Receivable, Net of Deferred Income	$ 8,656,945,000		7,642,143,000
Forecasted Value, National Unemployment, Percent	3.47%
Financing Receivable, before Allowance for Credit Loss	$ 8,656,945,000		7,642,143,000
Financing Receivable, Allowance for Credit Loss, Writeoff, after Recovery	1,200,000	1,100,000
Accrual Loans [Member] [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Troubled Debt Restructuring			6,400,000
Centric Bank
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Nonperforming, Nonaccrual of Interest	14,900,000
Net Deferred Fees
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Deferred Income	6,700,000		5,900,000
Unearned Premiums and Discounts
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Deferred Income	(33,500,000)		(5,400,000)
Financial Asset, 30 to 59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 12,854,000		15,896,000
Weighted average [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Forecasted Value, National Unemployment, Percent	4.42%
Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Forecasted Value, National Unemployment, Percent	4.84%
Time and Demand Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Charge-offs	$ 255,000
Loans and Leases Receivable, Gross	1,254,315,000		1,023,824,000
Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Charge-offs	0
Loans and Leases Receivable, Gross	484,193,000		431,151,000
Commercial, financial, agricultural and other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Charge-offs	663,000	475,000
Loans and Leases Receivable, Gross	1,471,079,000		1,211,706,000
Loans and Leases Receivable, Net of Deferred Income	1,471,079,000		1,211,706,000
Financing Receivable, before Allowance for Credit Loss	1,471,079,000		1,211,706,000
Commercial, financial, agricultural and other [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	1,470,000		1,233,000
Commercial, financial, agricultural and other [Member] | Time and Demand Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Charge-offs	255,000	144,000
Loans and Leases Receivable, Gross	1,254,315,000		1,023,824,000
Loans and Leases Receivable, Net of Deferred Income	1,254,315,000		1,023,824,000
Loans And Leases Receivable, Paycheck Protection Program	5,300,000		4,300,000
Financing Receivable, before Allowance for Credit Loss	1,254,315,000		1,023,824,000
Commercial, financial, agricultural and other [Member] | Time and Demand Loans | Financial Asset, 30 to 59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	1,462,000		1,121,000
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Charge-offs	0	0
Loans and Leases Receivable, Gross	2,991,930,000		2,425,012,000
Loans and Leases Receivable, Net of Deferred Income	2,991,930,000		2,425,012,000
Financing Receivable, before Allowance for Credit Loss	2,991,930,000		2,425,012,000
Commercial Real Estate [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	4,623,000		7,870,000
Commercial Real Estate [Member] | Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Charge-offs	0	0
Loans and Leases Receivable, Gross	484,193,000		431,151,000
Loans and Leases Receivable, Net of Deferred Income	484,193,000		431,151,000
Financing Receivable, before Allowance for Credit Loss	484,193,000		431,151,000
Commercial Real Estate [Member] | Multifamily | Financial Asset, 30 to 59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 68,000		202,000
Loans to individuals [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non Accrual Status Of Loans After Number Of Days Past Due	150 days
Nonaccrual Commercial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Held for sale, Amount	$ 0		$ 0
Loans and Leases Receivable, Gain (Loss) on Sales, Net	$ 0	$ 0