v3.25.2
Loans and allowance for loan losses - Loan Modification Activities to Borrowers Experiencing Financial Difficulty on Financing Receivables (Detail) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period $ 472,000 $ 441,000 $ 986,000 $ 916,000
Percent of Total Loan Class 0.35% 0.33% 0.73% 0.68%
Guaranteed by Government-Related Entities        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period $ 36,000 $ 47,000 $ 70,000 $ 88,000
Commercial and industrial        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period $ 87,000 $ 64,000 $ 223,000 $ 209,000
Percent of Total Loan Class 0.14% 0.11% 0.36% 0.35%
Commercial | Commercial Real Estate        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period $ 319,000 $ 168,000 $ 452,000 $ 377,000
Percent of Total Loan Class 1.58% 0.74% 2.24% 1.66%
Residential builder and developer | Commercial Real Estate        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period $ 0 $ 26,000 $ 0 $ 27,000
Percent of Total Loan Class 0.00% 2.49% 0.00% 2.62%
Other commercial construction | Commercial Real Estate        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period $ 12,000 $ 125,000 $ 214,000 $ 197,000
Percent of Total Loan Class 0.27% 2.18% 5.03% 3.44%
Residential | Residential Real Estate        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period $ 44,000 $ 58,000 $ 87,000 $ 105,000
Percent of Total Loan Class 0.18% 0.25% 0.36% 0.46%
Home equity lines and loans | Consumer        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period $ 0 $ 0 $ 0 $ 1,000
Percent of Total Loan Class 0.00% 0.00% 0.00% 0.03%
Recreational finance | Consumer        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period $ 0 $ 0 $ 0 $ 0
Percent of Total Loan Class 0.00% 0.00% 0.00% 0.00%
Automobile | Consumer        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period $ 0 $ 0 $ 0 $ 0
Percent of Total Loan Class 0.00% 0.00% 0.00% 0.00%
Other | Consumer        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period $ 10,000 $ 0 $ 10,000 $ 0
Percent of Total Loan Class 0.44% 0.00% 0.44% 0.00%
Unfunded Loan Commitment        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period $ 10,000 $ 1,000 $ 18,000 $ 27,000
Term Extension        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period 393,000 423,000 824,000 844,000
Term Extension | Commercial and industrial        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period 68,000 51,000 130,000 152,000
Term Extension | Commercial | Commercial Real Estate        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period 266,000 168,000 399,000 373,000
Term Extension | Residential builder and developer | Commercial Real Estate        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period 0 26,000 0 27,000
Term Extension | Other commercial construction | Commercial Real Estate        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period 12,000 125,000 214,000 197,000
Term Extension | Residential | Residential Real Estate        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period 37,000 53,000 71,000 95,000
Term Extension | Home equity lines and loans | Consumer        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period 0 0 0 0
Term Extension | Recreational finance | Consumer        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period 0 0 0 0
Term Extension | Automobile | Consumer        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period 0 0 0 0
Term Extension | Other | Consumer        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period 10,000 0 10,000 0
Other (a)        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period 70,000 17,000 74,000 65,000
Other (a) | Commercial and industrial        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period 16,000 13,000 17,000 57,000
Other (a) | Commercial | Commercial Real Estate        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period 53,000 0 53,000 0
Other (a) | Residential builder and developer | Commercial Real Estate        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period 0 0 0 0
Other (a) | Other commercial construction | Commercial Real Estate        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period 0 0 0 0
Other (a) | Residential | Residential Real Estate        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period 1,000 4,000 4,000 8,000
Other (a) | Home equity lines and loans | Consumer        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period 0 0 0 0
Other (a) | Recreational finance | Consumer        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period 0 0 0 0
Other (a) | Automobile | Consumer        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period 0 0 0 0
Other (a) | Other | Consumer        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period 0 0 0 0
Combination of Modification Types        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period 9,000 1,000 88,000 7,000
Combination of Modification Types | Commercial and industrial        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period 3,000 0 76,000 0
Combination of Modification Types | Commercial | Commercial Real Estate        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period 0 0 0 4,000
Combination of Modification Types | Residential builder and developer | Commercial Real Estate        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period 0 0 0 0
Combination of Modification Types | Other commercial construction | Commercial Real Estate        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period 0 0 0 0
Combination of Modification Types | Residential | Residential Real Estate        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period 6,000 1,000 12,000 2,000
Combination of Modification Types | Home equity lines and loans | Consumer        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period 0 0 0 1,000
Combination of Modification Types | Recreational finance | Consumer        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period 0 0 0 0
Combination of Modification Types | Automobile | Consumer        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period 0 0 0 0
Combination of Modification Types | Other | Consumer        
Financing Receivable, Modifications other than Troubled Debt Restructuring [Line Items]        
Modified in period $ 0 $ 0 $ 0 $ 0