Fair Value Measurement - Schedule of Fair Value of Assets and Liabilities Measured on Recurring and Nonrecurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	$ 11,453	$ 11,506
Available-for-sale debt securities	2,196,141	2,529,140
Loans held for sale	17,677	8,249
Other real estate owned and repossessed assets	1,333	1,486
Recurring Fair Value Measurements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	11,453	11,506
Available-for-sale debt securities	2,196,141	2,529,140
Loans held for sale	17,677	8,249
Other assets - interest rate swaps	97,215	75,840
Total assets	2,322,486	2,624,735
Other liabilities - interest rate swaps	95,567	74,683
Total liabilities recurring fair value measurements	95,567	74,683
Nonrecurring Fair Value Measurements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent loans	9,258	878
Other real estate owned and repossessed assets	1,333	1,486
Total assets	10,591	2,364
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	201,512	225,970
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	201,512	225,970
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	1,615,276	1,846,053
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	1,615,276	1,846,053
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	293,247	349,731
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	293,247	349,731
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	74,447	92,228
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	74,447	92,228
Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities	11,659	15,158
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	11,659	15,158
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	11,453	11,506
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	11,453	11,506
Total assets	11,453	11,506
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities	2,195,028	2,527,961
Loans held for sale	17,677	8,249
Other assets - interest rate swaps	97,215	75,840
Other liabilities - interest rate swaps	95,567	74,683
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	2,195,028	2,527,961
Loans held for sale	17,677	8,249
Other assets - interest rate swaps	97,215	75,840
Total assets	2,309,920	2,612,050
Other liabilities - interest rate swaps	95,567	74,683
Total liabilities recurring fair value measurements	95,567	74,683
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	201,512	225,970
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	1,615,276	1,846,053
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	293,247	349,731
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	73,334	91,049
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	11,659	15,158
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities	1,113	1,179
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	1,113	1,179
Total assets	1,113	1,179
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	9,258	878
Other real estate owned and repossessed assets	1,333	1,486
Total assets	10,591	2,364
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	$ 1,113	$ 1,179