v3.26.1
Fair Value Measurement - Estimates Fair Value of Financial Instruments (Detail) - USD ($)
$ in Thousands
Jun. 30, 2026
Dec. 31, 2025
Financial Assets    
Cash and due from banks $ 871,774 $ 956,109
Equity securities 19,060 30,809
Available-for-sale debt securities 3,312,972 3,288,332
Net held-to-maturity debt securities 1,107,751 1,132,114
Net loans 19,261,191 19,007,683
Loans held for sale 57,318 87,454
Accrued interest receivable 102,342 106,651
Financial Liabilities    
Deposits 21,592,216 21,668,840
Federal Home Loan Bank borrowings 1,350,000 1,200,000
Other borrowings 88,419 110,679
Subordinated debt and junior subordinated debt 308,837 308,529
Accrued interest payable 17,567 19,150
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]    
Financial Assets    
Cash and due from banks 871,774 956,109
Equity securities 19,060 30,809
Available-for-sale debt securities 195,957 196,857
Accrued interest receivable 102,342 106,651
Financial Liabilities    
Deposits 19,001,169 18,793,468
Other borrowings 82,023 105,240
Accrued interest payable 17,567 19,150
Significant Other Observable Inputs (Level 2) [Member]    
Financial Assets    
Available-for-sale debt securities 3,114,797 3,089,190
Net held-to-maturity debt securities 1,005,622 1,035,821
Loans held for sale 57,318 87,454
Other assets - interest rate derivatives 54,650 63,144
Financial Liabilities    
Deposits 2,575,033 2,863,653
Federal Home Loan Bank borrowings 1,350,079 1,200,761
Subordinated debt and junior subordinated debt 298,564 298,974
Other liabilities - interest rate derivatives 55,492 64,181
Significant Unobservable Inputs (Level 3) [Member]    
Financial Assets    
Available-for-sale debt securities 2,218 2,285
Net held-to-maturity debt securities 103 136
Net loans 18,901,935 18,563,341
Carrying Amount [Member]    
Financial Assets    
Cash and due from banks 871,774 956,109
Equity securities 19,060 30,809
Available-for-sale debt securities 3,312,972 3,288,332
Net held-to-maturity debt securities 1,107,586 1,131,946
Net loans 19,261,191 19,007,683
Loans held for sale 57,318 87,454
Other assets - interest rate derivatives 54,650 63,144
Accrued interest receivable 102,342 106,651
Financial Liabilities    
Deposits 21,592,216 21,668,840
Federal Home Loan Bank borrowings 1,350,000 1,200,000
Other borrowings 88,419 110,679
Subordinated debt and junior subordinated debt 308,837 308,529
Other liabilities - interest rate derivatives 55,492 64,181
Accrued interest payable 17,567 19,150
Fair Value Estimate [Member]    
Financial Assets    
Cash and due from banks 871,774 956,109
Equity securities 19,060 30,809
Available-for-sale debt securities 3,312,972 3,288,332
Net held-to-maturity debt securities 1,005,725 1,035,957
Net loans 18,901,935 18,563,341
Loans held for sale 57,318 87,454
Other assets - interest rate derivatives 54,650 63,144
Accrued interest receivable 102,342 106,651
Financial Liabilities    
Deposits 21,576,202 21,657,121
Federal Home Loan Bank borrowings 1,350,079 1,200,761
Other borrowings 82,023 105,240
Subordinated debt and junior subordinated debt 298,564 298,974
Other liabilities - interest rate derivatives 55,492 64,181
Accrued interest payable $ 17,567 $ 19,150