Loans and allowance for loan losses - Summary of Pledged Loans (Detail) - Asset Pledged as Collateral without Right - USD ($) $ in Thousands |
Jun. 30, 2026 |
Dec. 31, 2025 |
|---|---|---|
| Commercial and industrial | ||
| Loans And Leases Receivable [Line Items] | ||
| Pledged financial instruments | $ 23,600,000 | $ 20,700,000 |
| Commercial real estate | ||
| Loans And Leases Receivable [Line Items] | ||
| Pledged financial instruments | 13,300,000 | 13,400,000 |
| Residential real estate | ||
| Loans And Leases Receivable [Line Items] | ||
| Pledged financial instruments | 19,600,000 | 19,500,000 |
| Consumer | ||
| Loans And Leases Receivable [Line Items] | ||
| Pledged financial instruments | $ 17,400,000 | $ 18,200,000 |