Concentration Risk Threshold Percentage

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- Definition

Interest Bearing Time Deposits In Banks And Securities [Line Items]

+ References

No definition available.

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- Definition

Percentage of investment portfolio guaranteed by permanent school fund.

+ References

No definition available.

+ Details

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- Definition

Amount of realized gain 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/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-9

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- Definition

Number of investments in debt securities measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 320
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-Name Accounting Standards Codification
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- Definition

Amount of restricted investment in debt security measured at fair value with change in fair value recognized in net income (trading).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 860
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
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- Definition

Period of time between issuance and maturity of customer deposits, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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- Definition

Amount of cash inflow from sale of 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/2003/role/disclosureRef
-Topic 320
-SubTopic 10
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Securities - Additional Information (Detail)	3 Months Ended		9 Months Ended
Securities - Additional Information (Detail)	Sep. 30, 2025 USD ($) Investment	Sep. 30, 2024 USD ($)	Sep. 30, 2025 USD ($) Investment	Sep. 30, 2024 USD ($)	Dec. 31, 2024
Interest Bearing Time Deposits In Banks And Securities [Line Items]
Interest-bearing time deposits, maturity period, years	12 months	12 months	12 months	12 months	12 months
Number of investment positions \| Investment	682		682
Securities pledged as collateral	$ 2,335,928,000		$ 2,335,928,000
Debt Securities, Available-for-Sale, Realized Gain	0	$ 0	0	$ 0
Available-for-Sale Securities [Member]
Interest Bearing Time Deposits In Banks And Securities [Line Items]
Sales of investment securities available-for-sale	$ 0	$ 0	$ 0	$ 0
Obligations of State and Political Subdivisions [Member] \| Texas [Member]
Interest Bearing Time Deposits In Banks And Securities [Line Items]
Percentage of securities guaranteed by Texas Permanent School Fund	55.25%		55.25%
Obligations of State and Political Subdivisions [Member] \| Texas [Member] \| Available-for-Sale Securities [Member] \| Geographic Concentration Risk [Member]
Interest Bearing Time Deposits In Banks And Securities [Line Items]
Concentration risk threshold percentage			72.57%