Loans and Allowance for Credit Losses - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
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	$ 2,106,000	$ 4,839,000	$ 3,729,000	$ 8,604,000
Unfunded commitments related to nonperforming loans	100,000		100,000		$ 200,000
Off balance sheet reserve to nonperforming loans	0		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	0	0	0	0
Total gains or losses included in earnings	0	0	0	0
Recorded investment	35,692,000		35,692,000		55,180,000
Loans with modifications to rate and payment due to reamortization		169,000	10,000	169,000
Loans and Leases Receivable, Gross	7,119,754,000		7,119,754,000		6,839,230,000
Loans and Leases Receivable, Net of Deferred Income	7,119,754,000	6,740,535,000	$ 7,119,754,000	6,740,535,000	6,839,230,000
Forecasted Value, National Unemployment, Percent			3.58%
Financing Receivable, before Allowance for Credit Loss	7,119,754,000		$ 7,119,754,000		6,839,230,000
Financing Receivable, Allowance for Credit Loss, Writeoff, after Recovery			2,700,000	7,200,000
Net Deferred Fees
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Deferred Income	4,800,000		4,800,000		800,000
Unearned Premiums and Discounts
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Deferred Income	(5,700,000)		(5,700,000)		(6,000,000)
Financial Asset, 30 to 59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	4,844,000		$ 4,844,000		6,450,000
Weighted average [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Forecasted Value, National Unemployment, Percent			4.28%
Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Forecasted Value, National Unemployment, Percent			4.59%
Time and Demand Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	1,031,930,000		$ 1,031,930,000		1,159,524,000
Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	360,335,000		360,335,000		385,432,000
Commercial, financial, agricultural and other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Charge-offs	509,000	3,887,000	984,000	4,456,000
Loans and Leases Receivable, Gross	1,170,583,000		1,170,583,000		1,173,452,000
Loans and Leases Receivable, Net of Deferred Income	1,170,583,000	1,374,177,000	1,170,583,000	1,374,177,000	1,173,452,000
Financing Receivable, before Allowance for Credit Loss	1,170,583,000		1,170,583,000		1,173,452,000
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	121,000		121,000		633,000
Commercial, financial, agricultural and other [Member] | Time and Demand Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Charge-offs	139,000	3,878,000	283,000	4,338,000
Loans and Leases Receivable, Gross	1,031,930,000		1,031,930,000		1,159,524,000
Loans and Leases Receivable, Net of Deferred Income	1,031,930,000	1,360,065,000	1,031,930,000	1,360,065,000	1,159,524,000
Loans And Leases Receivable, Paycheck Protection Program	12,900,000		12,900,000		71,300,000
Financing Receivable, before Allowance for Credit Loss	1,031,930,000		1,031,930,000		1,159,524,000
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	14,000		14,000		605,000
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Charge-offs	552,000	7,000	552,000	1,557,000
Loans and Leases Receivable, Gross	2,319,094,000		2,319,094,000		2,251,097,000
Loans and Leases Receivable, Net of Deferred Income	2,319,094,000	2,205,758,000	2,319,094,000	2,205,758,000	2,251,097,000
Financing Receivable, before Allowance for Credit Loss	2,319,094,000		2,319,094,000		2,251,097,000
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	76,000		76,000		0
Commercial Real Estate [Member] | Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Charge-offs	411,000	0	411,000	1,000
Loans and Leases Receivable, Gross	360,335,000		360,335,000		385,432,000
Loans and Leases Receivable, Net of Deferred Income	360,335,000	$ 385,905,000	360,335,000	385,905,000	385,432,000
Financing Receivable, before Allowance for Credit Loss	360,335,000		360,335,000		385,432,000
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	76,000		$ 76,000		0
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		$ 0
Loans and Leases Receivable, Gain (Loss) on Sales, Net			$ 0	$ 0