Concentration of loans in a single industry in excess of ten percent

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Maximum Percentage of Loan Related To Single Industry

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Number Of Days Past Due

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Percent Of Valuation Allowance In Excess Of Principal Balance Maximum

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Percent Of Valuation Allowance In Excess Of Principal Balance Minimum

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Percentage of total energy loans to total loans

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- Definition

Texas Leading Index economic condition indicator

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U.S. dollar denominated loans and commitments to borrowers in Mexico

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Unfunded balances

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Weighted Average Risk Grade for Loans

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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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Carrying value as of the balance sheet date of payments made in excess of existing cash balances, which will be honored by the bank but reflected as a loan to the entity. Overdrafts generally have a very short time frame for correction or repayment and are therefore more similar to short-term bank financing than trade financing.

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Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

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Threshold period for when financing receivable is considered past due, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Excludes threshold period past due to write off as uncollectible.

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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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Reflects the amount of additional interest income that would have been recorded if impaired or nonperforming loans were instead current, in compliance with their original terms, and outstanding throughout the reporting period or since origination (if held for part of the period).

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Loans (Narrative) (Detail) $ in Thousands	12 Months Ended
Loans (Narrative) (Detail) $ in Thousands	Dec. 31, 2022 USD ($) Grade	Dec. 31, 2021 USD ($) Grade	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration of loans in a single industry in excess of ten percent	0.00%	0.00%
Maximum percentage loan related to single industry	10.00%	10.00%
U.S. dollar denominated loans and commitments to borrowers in Mexico	$ 0	$ 0
Commercial and industrial loans related to overdraft for correspondent bank customer	$ 10,300	$ 7,800
Financing Receivable, Threshold Period Past Due	90 days
Number of days past due for payment of interest on loans, minimum	120 days
Texas Leading Index economic condition indicator	129.7	135.7
Financing Receivable, Allowance for Credit Loss	$ 227,621	$ 248,666
Loans Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accrued interest receivable	$ 68,700	$ 40,000
Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of total energy loans to total loans	5.40%	6.60%
Weighted Average Risk Grade \| Grade	5.67	6.06
Financing Receivable, Allowance for Credit Loss	$ 18,062	$ 17,217	$ 39,553	$ 37,382
Commercial and Industrial Total Energy Loans [Member] \| Risk Grade One To Eight [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade \| Grade	5.44	5.78
Non Accrual Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Additional interest that would have been recognized on non-accrual loans, net of tax	$ 1,700	$ 1,800	2,900
Grade 12 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
General percentage of valuation allowance in excess of principal balance, maximum	30.00%
Grade 13 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
General percentage of valuation allowance in excess of principal balance, minimum	30.00%
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade \| Grade	6.39	6.22
Financing Receivable, Allowance for Credit Loss	$ 104,237	$ 72,091	73,843	51,593
Commercial Portfolio Segment [Member] \| Risk Grade One To Eight [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade \| Grade	6.24	6.01
Commercial and Industrial, Other Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of days past due for payment of interest on loans, minimum	180 days
Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade \| Grade	7.10	7.19
Financing Receivable, Allowance for Credit Loss	$ 90,301	$ 144,936	134,892	31,037
Commercial Real Estate Buildings Land And Other Financing Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade \| Grade	7.09	7.22
Commercial Real Estate Buildings Land And Other Financing Receivable [Member] \| Risk Grade One To Eight [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade \| Grade	6.94	6.91
Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade \| Grade	7.12	7.06
Construction Loans [Member] \| Risk Grade One To Eight [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade \| Grade	7.04	6.99
Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Allowance for Credit Loss	$ 7,017	$ 7,837	6,963	$ 8,042
Paycheck Protection Program [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Allowance for Credit Loss	0	$ 0	$ 0
Commitments to Extend Credit [Member] \| Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded balances	997,100
Standby Letters of Credit [Member] \| Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded balances	$ 103,400