Fair Value Disclosures - Schedule of Estimated Fair Values and Carrying Values of All Financial Instruments (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
CASH AND DUE FROM BANKS	$ 205,053	$ 211,113
INTEREST-BEARING DEMAND DEPOSITS IN BANKS	323,535	517,971
Securities available-for-sale, Estimated Fair Value	6,573,179	4,393,029
Loans held-for-investment, net of allowance for credit losses	5,325,507	5,104,499
Held-for-sale ($34,122 and $79,585 at fair value as of December 31, 2021 and 2020, respectively)	37,810	83,969
Deposits with stated maturities	461,415
BORROWINGS	671,152	430,093
IRLCs [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Asset Derivative Fair Value	1,279	4,618
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	0
Liability Derivative Fair Value	147	1,560
Level 1 Inputs [Member] \| Carrying Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
CASH AND DUE FROM BANKS	205,053	211,113
INTEREST-BEARING DEMAND DEPOSITS IN BANKS	323,535	517,971
Deposits with no stated maturities	10,105,073	8,200,275
Level 1 Inputs [Member] \| Estimated Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
CASH AND DUE FROM BANKS	205,053	211,113
INTEREST-BEARING DEMAND DEPOSITS IN BANKS	323,535	517,971
Deposits with no stated maturities	10,105,073	8,200,275
Levels 1 and 2 Inputs [Member] \| Carrying Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Securities available-for-sale, Estimated Fair Value	6,573,179	4,393,029
Levels 1 and 2 Inputs [Member] \| Estimated Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Securities available-for-sale, Estimated Fair Value	6,573,179	4,393,029
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	5,325,507	5,104,499
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	5,335,791	5,109,885
Level 2 Inputs [Member] \| Carrying Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Held-for-sale ($34,122 and $79,585 at fair value as of December 31, 2021 and 2020, respectively)	37,810	83,969
Accrued interest receivable	57,169	53,433
Deposits with stated maturities	461,415	475,542
BORROWINGS	671,152	430,093
Accrued interest payable	221	377
Level 2 Inputs [Member] \| Carrying Value [Member] \| IRLCs [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Asset Derivative Fair Value	1,279	4,618
Level 2 Inputs [Member] \| Carrying Value [Member] \| Forward Mortgage-Backed Securities Trades [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Liability Derivative Fair Value	(147)	(1,560)
Level 2 Inputs [Member] \| Estimated Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Held-for-sale ($34,122 and $79,585 at fair value as of December 31, 2021 and 2020, respectively)	37,844	84,233
Accrued interest receivable	57,169	53,433
Deposits with stated maturities	462,312	477,218
BORROWINGS	671,152	430,093
Accrued interest payable	221	377
Level 2 Inputs [Member] \| Estimated Fair Value [Member] \| IRLCs [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Asset Derivative Fair Value	1,279	4,618
Level 2 Inputs [Member] \| Estimated Fair Value [Member] \| Forward Mortgage-Backed Securities Trades [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Liability Derivative Fair Value	$ (147)	$ (1,560)

Accrued interest payable.

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Deposits with no stated maturities.

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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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