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Securities - Additional Information (Detail)
3 Months Ended 6 Months Ended 9 Months Ended
Sep. 30, 2022
USD ($)
Investment
Sep. 30, 2021
USD ($)
Jun. 30, 2022
Sep. 30, 2022
USD ($)
Investment
Sep. 30, 2021
USD ($)
Dec. 31, 2021
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      
Number of investment positions | Investment 1,115     1,115    
Securities pledged as collateral $ 3,447,317,000     $ 3,447,317,000    
Sales of investment securities available-for-sale 17,081,000     205,444,000 10,631,000  
Gross realized gains from security sales $ 334,000 $ 1,000   4,357,000 814,000  
Gross realized losses from security sales or calls       $ 2,344,000 $ 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 55.16%     55.16%    
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       72.44%