v3.26.1
Fair Value - Carrying Amount and Estimated Fair Values of Financial Instrument (Detail) - USD ($)
Mar. 31, 2026
Dec. 31, 2025
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Cash and cash equivalents $ 564,165,000 $ 607,817,000
Available-for-sale securities 1,125,162,000 1,030,568,000
Interest-bearing deposit in other banks 932,000 575,000
Held-to-maturity securities 5,346,000 5,409,000
Loans held for sale 7,631,000 1,392,000
Loans, net of allowance for credit losses 5,364,030,000 4,145,424,000
Federal Reserve Bank and Federal Home Loan Bank stock 38,806,000 34,053,000
Interest receivable 39,966,000 33,322,000
Derivative assets 5,547,000 5,758,000
Total assets 7,667,370,000 6,373,172,000
Deposits 6,300,910,000 5,138,264,000
Federal funds purchased and retail repurchase agreements 39,009,000 39,864,000
Federal Home Loan Bank advances 347,660,000 300,000,000
Subordinated debentures 98,263,000 98,145,000
Contractual obligations 9,678,000 10,208,000
Derivative Liabilities 2,723,000 2,808,000
Cash collateral held by counterparty and netting adjustments (3,898,000) (3,367,000)
Total liabilities 6,849,760,000 5,641,118,000
Carrying Amount [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Cash and cash equivalents 564,165,000 607,817,000
Available-for-sale securities 1,125,162,000 1,030,568,000
Interest-bearing deposit in other banks 932,000 575,000
Held-to-maturity securities 5,254,000 5,248,000
Loans held for sale 7,631,000 1,392,000
Loans, net of allowance for credit losses 5,364,030,000 4,145,424,000
Federal Reserve Bank and Federal Home Loan Bank stock 38,806,000 34,053,000
Interest receivable 39,966,000 33,322,000
Derivative assets 5,547,000 5,758,000
Cash collateral held by derivative counterparty and netting adjustments (3,898,000) (3,367,000)
Total derivative assets 1,649,000 2,391,000
Equity securities with readily determinable fair value 1,404,000 1,182,000
Total assets 7,148,999,000 5,861,972,000
Deposits 6,300,910,000 5,138,264,000
Federal funds purchased and retail repurchase agreements 39,009,000 39,864,000
Federal Home Loan Bank advances 347,660,000 300,000,000
Subordinated debentures 24,401,000 24,308,000
Subordinated notes 73,862,000 73,837,000
Contractual obligations 9,678,000 10,208,000
Interest payable 7,421,000 9,757,000
Derivative Liabilities 2,723,000 2,808,000
Cash collateral held by counterparty and netting adjustments 281,000 (8,000)
Total derivative liabilities 3,004,000 2,800,000
Total liabilities 6,805,945,000 5,599,038,000
Estimated Fair Value [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Cash and cash equivalents 564,165,000 607,817,000
Available-for-sale securities 1,125,162,000 1,030,568,000
Interest-bearing deposit in other banks 932,000 575,000
Held-to-maturity securities 5,346,000 5,409,000
Loans held for sale 7,631,000 1,392,000
Loans, net of allowance for credit losses 5,179,690,000 4,126,632,000
Federal Reserve Bank and Federal Home Loan Bank stock 38,806,000 34,053,000
Interest receivable 39,966,000 33,322,000
Derivative assets 5,547,000 5,758,000
Cash collateral held by derivative counterparty and netting adjustments (3,898,000) (3,367,000)
Total derivative assets 1,649,000 2,391,000
Equity securities with readily determinable fair value 1,404,000 1,182,000
Deposits 6,295,455,000 5,135,904,000
Federal funds purchased and retail repurchase agreements 39,009,000 39,864,000
Federal Home Loan Bank advances 347,660,000 300,000,000
Subordinated debentures 24,401,000 24,308,000
Subordinated notes 75,362,000 75,524,000
Contractual obligations 9,678,000 10,208,000
Interest payable 7,421,000 9,757,000
Derivative Liabilities 2,723,000 2,808,000
Cash collateral held by counterparty and netting adjustments 281,000 (8,000)
Total derivative liabilities 3,004,000 2,800,000
Total liabilities 6,801,990,000 5,598,365,000
Estimated Fair Value [Member] | Level 1 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Cash and cash equivalents 564,165,000 607,817,000
Available-for-sale securities 38,731,000 35,250,000
Cash collateral held by derivative counterparty and netting adjustments (3,898,000) (3,367,000)
Total derivative assets (3,898,000) (3,367,000)
Equity securities with readily determinable fair value 1,404,000 1,182,000
Cash collateral held by counterparty and netting adjustments 281,000 (8,000)
Total derivative liabilities 281,000 (8,000)
Total liabilities 281,000 (8,000)
Estimated Fair Value [Member] | Level 2 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Available-for-sale securities 1,086,431,000 995,318,000
Interest-bearing deposit in other banks 932,000 575,000
Held-to-maturity securities 5,346,000 5,409,000
Loans held for sale 7,631,000 1,392,000
Federal Reserve Bank and Federal Home Loan Bank stock 38,806,000 34,053,000
Interest receivable 39,966,000 33,322,000
Derivative assets 5,547,000 5,758,000
Total derivative assets 5,547,000 5,758,000
Deposits 6,295,455,000 5,135,904,000
Federal funds purchased and retail repurchase agreements 39,009,000 39,864,000
Federal Home Loan Bank advances 347,660,000 300,000,000
Subordinated debentures 24,401,000 24,308,000
Subordinated notes 75,362,000 75,524,000
Contractual obligations 9,678,000 10,208,000
Interest payable 7,421,000 9,757,000
Derivative Liabilities 2,723,000 2,808,000
Total derivative liabilities 2,723,000 2,808,000
Total liabilities 6,801,709,000 5,598,373,000
Estimated Fair Value [Member] | Level 3 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans, net of allowance for credit losses 5,179,690,000 4,126,632,000
Fair Value, Measurements, Nonrecurring [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Total liabilities 0 0
Fair Value, Measurements, Nonrecurring [Member] | Estimated Fair Value [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Total assets 6,964,751,000 5,843,341,000
Fair Value, Measurements, Nonrecurring [Member] | Estimated Fair Value [Member] | Level 1 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Total assets 600,402,000 640,882,000
Fair Value, Measurements, Nonrecurring [Member] | Estimated Fair Value [Member] | Level 2 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Total assets 1,184,659,000 1,075,827,000
Fair Value, Measurements, Nonrecurring [Member] | Estimated Fair Value [Member] | Level 3 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Total assets $ 5,179,690,000 $ 4,126,632,000