Securities - Additional Information (Detail)	12 Months Ended
Dec. 31, 2022 USD ($) Investment	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Interest Bearing Time Deposits In Banks And Securities [Line Items]
INTEREST-BEARING TIME DEPOSITS IN BANKS	$ 0	$ 0
Interest-bearing time deposits, maturity period, years		12 months
Number of investment positions \| Investment	1,004
Securities pledged as collateral	$ 4,070,454,000	$ 3,644,626,000
Sales of investment securities available-for-sale	479,273,000	10,631,000	$ 263,042,000
Gross realized gains from security sales or calls	6,618,000	$ 815,000	3,637,000
Gross realized losses from security sales or calls	$ 4,474,000		$ 4,000
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	54.77%	53.94%
Obligations of State and Political Subdivisions [Member] \| Texas [Member] \| Geographic Concentration Risk [Member] \| Available-for-Sale Securities [Member]
Interest Bearing Time Deposits In Banks And Securities [Line Items]
Concentration risk, percentage	71.86%	72.72%

Interest-bearing time deposits in banks.

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

+ References

No definition available.

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Percentage of investment portfolio guaranteed by permanent school fund.

+ References

No definition available.

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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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-Publisher FASB
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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).

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Amount of realized 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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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.

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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.

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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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