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Securities - Additional Information (Detail) - USD ($) $ in Thousands | 3 Months Ended |
--- | --- | ---
Mar. 31, 2022 | Mar. 31, 2021 | Dec. 31, 2021
Schedule Of Marketable Securities [Line Items] |  |  |
AOCI, Debt Securities, Available-for-sale, Adjustment, Pre Tax | $ 2,300 |  | $ 2,500
Net unamortized unrealized gain on transferred securities included in accumulated other comprehensive income, net of tax | $ 1,800 |  | 2,000
Percent Municipal Bond Portfolio Issued By Political Subdivision Or Agencies Within State Of Texas Guaranteed By Texas Permanent School Fund Or Have Been Pre-Refunded | 75.70% |  |
Debt Securities, Available-for-sale, Allowance for Credit Loss | $ 0 |  | 0
Proceeds from Sale of Debt Securities, Available-for-sale | 0 | $ 0 |
Proceeds from Sale of Held-to-maturity Securities | 0 | $ 0 |
Held-to-maturity Securities [Member] |  |  |
Schedule Of Marketable Securities [Line Items] |  |  |
Carry value of securities pledged | 252,000 |  | 642,300
Accrued interest receivable | 10,000 |  | 18,400
Available-for-sale Securities [Member] |  |  |
Schedule Of Marketable Securities [Line Items] |  |  |
Carry value of securities pledged | 4,800,000 |  | 5,800,000
Accrued interest receivable | $ 80,800 |  | $ 120,500

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- Definition Amount, after tax, of accumulated unrealized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14 -URI http://asc.fasb.org/extlink&oid=124509347&loc=d3e681-108580 + Details
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