Fair Value Disclosures - Schedule of Estimated Fair Values and Carrying Values of All Financial Instruments (Detail) - USD ($)	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash and due from banks	$ 281,354,000	$ 293,286,000
Interest-bearing demand deposits in banks	255,237,000	37,392,000
Securities available-for-sale, at fair value	4,732,762,000	5,474,359,000
Loans held-for-investment, net of allowance for credit losses	7,060,057,000	6,366,034,000
Loans held-for-sale	14,253,000	11,965,000
Deposits with stated maturities	938,980,000
Borrowings	22,153,000	23,678,000
IRLCs [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Asset Derivative Fair Value	427,000	400,000
Liability Derivative Fair Value	0	0
Forward Mortgage-Backed Securities Trades [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Asset Derivative Fair Value	0	85,000
Liability Derivative Fair Value	(288,000)	0
Level 1 Inputs [Member] \| Carrying Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash and due from banks	281,354,000	293,286,000
Interest-bearing demand deposits in banks	255,237,000	37,392,000
Deposits with no stated maturities	10,199,320,000	10,480,841,000
Level 1 Inputs [Member] \| Estimated Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash and due from banks	281,354,000	293,286,000
Interest-bearing demand deposits in banks	255,237,000	37,392,000
Deposits with no stated maturities	10,199,320,000	10,480,841,000
Level 1 Inputs [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Securities available-for-sale, at fair value	0
Levels 1 and 2 Inputs [Member] \| Carrying Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Securities available-for-sale, at fair value	4,732,762,000	5,474,359,000
Levels 1 and 2 Inputs [Member] \| Estimated Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Securities available-for-sale, at fair value	4,732,762,000	5,474,359,000
Level 3 Inputs [Member] \| Carrying Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Loans held-for-investment, net of allowance for credit losses	7,060,057,000	6,366,034,000
Level 3 Inputs [Member] \| Estimated Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Loans held-for-investment, net of allowance for credit losses	7,036,722,000	6,372,859,000
Level 3 Inputs [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Securities available-for-sale, at fair value	0
Level 2 Inputs [Member] \| Carrying Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Loans held-for-sale	14,253,000	11,965,000
Accrued interest receivable	58,544,000	58,162,000
Deposits with stated maturities	938,980,000	524,666,000
Repurchase Agreements	381,928,000	618,829,000
Borrowings	22,153,000	23,678,000
Accrued interest payable	10,215,000	1,121,000
Level 2 Inputs [Member] \| Estimated Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Loans held-for-sale	14,378,000	11,965,000
Accrued interest receivable	58,544,000	58,162,000
Deposits with stated maturities	938,534,000	518,811,000
Repurchase Agreements	381,928,000	618,829,000
Borrowings	22,153,000	23,678,000
Accrued interest payable	10,215,000	1,121,000
Level 2 Inputs [Member] \| IRLCs [Member] \| Carrying Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Asset Derivative Fair Value	427,000	400,000
Level 2 Inputs [Member] \| IRLCs [Member] \| Estimated Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Asset Derivative Fair Value	427,000	400,000
Level 2 Inputs [Member] \| Forward Mortgage-Backed Securities Trades [Member] \| Carrying Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Liability Derivative Fair Value	(288,000)	85,000
Level 2 Inputs [Member] \| Forward Mortgage-Backed Securities Trades [Member] \| Estimated Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Liability Derivative Fair Value	$ (288,000)	$ 85,000

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Deposits with no stated maturities.

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Repurchase Agreements

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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For banks and other depository institutions: Includes cash on hand (currency and coin), cash items in process of collection, noninterest bearing deposits due from other financial institutions (including corporate credit unions), and noninterest bearing balances with the Federal Reserve Banks, Federal Home Loan Banks and central banks.

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Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

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Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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For banks and other depository institutions (including Federal Reserve Banks, if applicable): Interest-bearing deposits in other financial institutions for relatively short periods of time including, for example, certificates of deposits, which are presented separately from cash on the balance sheet.

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Carrying amount as of the balance sheet date of interest earned but not received. Also called accrued interest or accrued interest receivable.

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Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale.

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Amount, after valuation allowance, of financing receivable held for sale and not part of disposal group. Excludes loan covered under loss sharing agreement and loan classified as investment in debt security.

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Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

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Amount of time deposit liabilities, including certificates of deposit.

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