Interest-bearing time deposits in banks.

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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.

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- Definition

Amount of unrealized 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/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
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-Paragraph 2
-Subparagraph (b)
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- Definition

Amount of unrealized loss on 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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- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

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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

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

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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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Industry Guide
-Number 3
-Section V
-Paragraph D-E
-Publisher SEC

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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).

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Securities - Additional Information (Detail)	3 Months Ended		9 Months Ended
Securities - Additional Information (Detail)	Sep. 30, 2023 USD ($) Investment	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) Investment	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)
Interest Bearing Time Deposits In Banks And Securities [Line Items]
Interest Bearing Time Deposits In Banks	$ 0	$ 0	$ 0	$ 0	$ 0
Interest-bearing time deposits, maturity period, years	12 months		12 months		12 months
Number of investment positions \| Investment	892		892
Securities pledged as collateral	$ 3,397,495,000		$ 3,397,495,000
Sales of investment securities available-for-sale			320,419,000	205,444,000
Gross realized gains from security sales	53,000	334,000	1,701,000	4,357,000
Gross realized losses from security sales or calls	1,025,000		2,615,000	2,344,000
Available-for-Sale Securities [Member]
Interest Bearing Time Deposits In Banks And Securities [Line Items]
Sales of investment securities available-for-sale	$ 113,132,000	$ 17,081,000	$ 320,419,000	$ 205,444,000
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	56.47%		56.47%
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, percentage			66.92%