v3.26.3
Fair Value Measurement - Schedule of Fair Value of Assets and Liabilities Measured on Recurring and Nonrecurring Basis (Detail) - USD ($)
$ in Thousands
Sep. 30, 2026
Dec. 31, 2025
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Equity securities $ 18,303 $ 30,809
Available-for-sale debt securities 3,353,692 3,288,332
Loans held for sale, fair value 37,545 87,454
Other real estate owned and repossessed assets 1,784 907
Recurring Fair Value Measurements [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Equity securities 18,303 30,809
Available-for-sale debt securities 3,353,692 3,288,332
Loans held for sale, fair value 37,545 87,454
Other assets - interest rate derivatives agreements 99,078 63,144
Total assets recurring fair value measurements 3,508,618 3,469,739
Other liabilities - interest rate derivatives agreements 97,876 64,181
Total liabilities recurring fair value measurements 97,876 64,181
Nonrecurring Fair Value Measurements [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Collateral dependent loans 27,643 20,400
Other real estate owned and repossessed assets 1,784 907
Total assets recurring fair value measurements 29,427 21,307
U.S. Treasury [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities 196,710 196,857
U.S. Treasury [Member] | Recurring Fair Value Measurements [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities 196,710 196,857
U.S. Government Sponsored Entities and Agencies [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities 197,728 222,997
U.S. Government Sponsored Entities and Agencies [Member] | Recurring Fair Value Measurements [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities 197,728 222,997
Residential Mortgage-Backed Securities and Collateralized Mortgage Obligations of Government Sponsored Entities and Agencies [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities 2,729,247 2,610,448
Residential Mortgage-Backed Securities and Collateralized Mortgage Obligations of Government Sponsored Entities and Agencies [Member] | Recurring Fair Value Measurements [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities 2,729,247 2,610,448
Commercial Mortgage-Backed Securities and Collateralized Mortgage Obligations of Government Sponsored Entities and Agencies [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities 52,650 63,615
Commercial Mortgage-Backed Securities and Collateralized Mortgage Obligations of Government Sponsored Entities and Agencies [Member] | Recurring Fair Value Measurements [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities 52,650 63,615
Asset Backed Securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities 63,601 68,935
Asset Backed Securities [Member] | Recurring Fair Value Measurements [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities 63,601 68,935
Obligations of States and Political Subdivisions [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities 74,077 73,188
Obligations of States and Political Subdivisions [Member] | Recurring Fair Value Measurements [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities 74,077 73,188
Corporate Debt Securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities 39,679 52,292
Corporate Debt Securities [Member] | Recurring Fair Value Measurements [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities 39,679 52,292
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Recurring Fair Value Measurements [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Equity securities 18,303 30,809
Available-for-sale debt securities 196,710 196,857
Total assets recurring fair value measurements 215,013 227,666
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | U.S. Treasury [Member] | Recurring Fair Value Measurements [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities 196,710 196,857
Significant Other Observable Inputs (Level 2) [Member] | Recurring Fair Value Measurements [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities 3,154,876 3,089,190
Loans held for sale, fair value 37,545 87,454
Other assets - interest rate derivatives agreements 99,078 63,144
Total assets recurring fair value measurements 3,291,499 3,239,788
Other liabilities - interest rate derivatives agreements 97,876 64,181
Total liabilities recurring fair value measurements 97,876 64,181
Significant Other Observable Inputs (Level 2) [Member] | U.S. Government Sponsored Entities and Agencies [Member] | Recurring Fair Value Measurements [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities 197,728 222,997
Significant Other Observable Inputs (Level 2) [Member] | Residential Mortgage-Backed Securities and Collateralized Mortgage Obligations of Government Sponsored Entities and Agencies [Member] | Recurring Fair Value Measurements [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities 2,729,247 2,610,448
Significant Other Observable Inputs (Level 2) [Member] | Commercial Mortgage-Backed Securities and Collateralized Mortgage Obligations of Government Sponsored Entities and Agencies [Member] | Recurring Fair Value Measurements [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities 52,650 63,615
Significant Other Observable Inputs (Level 2) [Member] | Asset Backed Securities [Member] | Recurring Fair Value Measurements [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities 63,601 68,935
Significant Other Observable Inputs (Level 2) [Member] | Obligations of States and Political Subdivisions [Member] | Recurring Fair Value Measurements [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities 71,971 70,903
Significant Other Observable Inputs (Level 2) [Member] | Corporate Debt Securities [Member] | Recurring Fair Value Measurements [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities 39,679 52,292
Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities 2,106 2,285
Total assets recurring fair value measurements 2,106 2,285
Significant Unobservable Inputs (Level 3) [Member] | Nonrecurring Fair Value Measurements [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Collateral dependent loans 27,643 20,400
Other real estate owned and repossessed assets 1,784 907
Total assets recurring fair value measurements 29,427 21,307
Significant Unobservable Inputs (Level 3) [Member] | Obligations of States and Political Subdivisions [Member] | Recurring Fair Value Measurements [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities $ 2,106 $ 2,285