v3.26.1
Fair Value Measurements - Summary of Estimated Fair Values of Financial Instruments (Detail) - USD ($)
$ in Thousands
Jun. 30, 2026
Dec. 31, 2025
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Cash and cash equivalents $ 2,081,303 $ 2,542,250
Securities available for sale 3,319,750 3,059,452
Securities held to maturity 1,006 1,004
Other securities 308,168 305,184
Loans held for sale 35,224 31,277
Net loans 24,994,524 24,709,122
Derivative financial assets 1,198 789
Deposits 27,170,747 27,060,939
Derivative financial liabilities 78 70
Carrying Amount [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Cash and cash equivalents 2,081,303 2,542,250
Securities available for sale 3,319,750 3,059,452
Securities held to maturity 1,006 1,004
Other securities 308,168 305,184
Loans held for sale 35,224 31,277
Net loans 24,695,020 24,411,604
Derivative financial assets 1,198 789
Deposits 27,170,747 27,060,939
Short-term borrowings 166,996 198,573
Long-term borrowings 532,615 531,817
Derivative financial liabilities 78 70
Carrying Amount [Member] | Marketable Equity Securities [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Equity securities 30,107 34,760
Fair Value [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Cash and cash equivalents 2,081,303 2,542,250
Securities available for sale 3,319,750 3,059,452
Securities held to maturity 1,020 1,020
Other securities 292,760 289,925
Loans held for sale 35,224 31,277
Net loans 24,611,507 24,432,980
Derivative financial assets 1,198 789
Deposits 27,130,646 27,031,873
Short-term borrowings 166,996 198,573
Long-term borrowings 527,456 524,281
Derivative financial liabilities 78 70
Fair Value [Member] | Marketable Equity Securities [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Equity securities 30,107 34,760
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Cash and cash equivalents 0 0
Securities available for sale 4,514 4,678
Securities held to maturity 0 0
Other securities 0 0
Loans held for sale 0 0
Net loans 0 0
Derivative financial assets 0 0
Deposits 0 0
Short-term borrowings 0 0
Long-term borrowings 0 0
Derivative financial liabilities 0 0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Marketable Equity Securities [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Equity securities 30,107 29,356
Significant Other Observable Inputs (Level 2) [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Cash and cash equivalents 2,081,303 2,542,250
Securities available for sale 3,315,236 3,054,774
Securities held to maturity 0 0
Other securities 0 0
Loans held for sale 0 0
Net loans 0 0
Derivative financial assets 394 316
Deposits 27,130,646 27,031,873
Short-term borrowings 166,996 198,573
Long-term borrowings 527,456 524,281
Derivative financial liabilities 0 70
Significant Other Observable Inputs (Level 2) [Member] | Marketable Equity Securities [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Equity securities 0 5,404
Significant Unobservable Inputs (Level 3) [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Cash and cash equivalents 0 0
Securities available for sale 0 0
Securities held to maturity 1,020 1,020
Other securities 292,760 289,925
Loans held for sale 35,224 31,277
Net loans 24,611,507 24,432,980
Derivative financial assets 804 473
Deposits 0 0
Short-term borrowings 0 0
Long-term borrowings 0 0
Derivative financial liabilities 78 0
Significant Unobservable Inputs (Level 3) [Member] | Marketable Equity Securities [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Equity securities $ 0 $ 0