Deposits (Additional Information About Corporation's Deposits) (Detail) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Deposit Liability [Line Items]
Deposits from foreign sources (primarily Mexico)	$ 1,265,896	$ 1,219,463
Non-interest-bearing public funds deposits	14,143,815	14,441,820
Interest-bearing public funds deposits	28,774,049	28,280,928
Total deposits not covered by deposit insurance	22,286,545	22,972,618
Time deposits not covered by deposit insurance	2,877,253	2,744,112
Deposits from certain directors, executive officers and their affiliates	101,522	121,113
Public Funds [Member]
Deposit Liability [Line Items]
Non-interest-bearing public funds deposits	662,354	759,819
Interest-bearing public funds deposits	$ 768,726	$ 625,104

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.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Amount of uninsured deposit liability.

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The aggregate of all foreign interest-bearing and noninterest-bearing deposit liabilities.

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The aggregate amount of all domestic and foreign noninterest-bearing deposits liabilities held by the entity.

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Amount of deposits held by the entity for a related party (entity, shareholder, employee).

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Amount of uninsured time deposit liability in excess of Federal Deposit Insurance Corporation (FDIC) insurance limit or similar state deposit insurance regime in United States of America (US). Excludes time deposit that is otherwise uninsured.

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