Fair Value Disclosures - Schedule of Estimated Fair Values and Carrying Values of All Financial Instruments (Detail) - USD ($)	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash and due from banks	$ 259,996,000	$ 281,354,000
Interest-bearing demand deposits in banks	503,417,000	255,237,000
Securities available-for-sale, at fair value	4,617,759,000	4,732,762,000
Loans held-for-investment, net of allowance for credit losses	7,814,773,000	7,060,057,000
Loans held for sale	8,235,000	14,253,000
Deposits with stated maturities	917,276,000
Borrowings	135,603,000	22,153,000
IRLCs [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Asset Derivative Fair Value	238,000	427,000
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	84,000	0
Liability Derivative Fair Value	0	(288,000)
Level 1 Inputs [Member] \| Carrying Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash and due from banks	259,996,000	281,354,000
Interest-bearing demand deposits in banks	503,417,000	255,237,000
Deposits with no stated maturities	11,181,898,000	10,199,320,000
Level 1 Inputs [Member] \| Estimated Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash and due from banks	259,996,000	281,354,000
Interest-bearing demand deposits in banks	503,417,000	255,237,000
Deposits with no stated maturities	11,181,898,000	10,199,320,000
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	4,617,759,000	4,732,762,000
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	4,617,759,000	4,732,762,000
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	7,814,773,000	7,060,057,000
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	7,806,258,000	7,036,722,000
Level 2 Inputs [Member] \| Carrying Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Loans held for sale	8,235,000	14,253,000
Accrued interest receivable	60,749,000	58,544,000
Deposits with stated maturities	917,276,000	938,980,000
Repurchase Agreements	61,416,000	381,928,000
Borrowings	135,603,000	22,153,000
Accrued interest payable	6,909,000	10,215,000
Level 2 Inputs [Member] \| Estimated Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Loans held for sale	8,276,000	14,378,000
Accrued interest receivable	60,749,000	58,544,000
Deposits with stated maturities	919,774,000	938,534,000
Repurchase Agreements	61,416,000	381,928,000
Borrowings	135,603,000	22,153,000
Accrued interest payable	6,909,000	10,215,000
Level 2 Inputs [Member] \| IRLCs [Member] \| Carrying Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Asset Derivative Fair Value	238,000	427,000
Level 2 Inputs [Member] \| IRLCs [Member] \| Estimated Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Asset Derivative Fair Value	238,000	427,000
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	84,000	(288,000)
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	$ 84,000	$ (288,000)

Accrued interest payable.

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Deposits with no stated maturities.

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Loan And Leases Receivable Net Reported Amount

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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 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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