Fair Value of Financial Instruments - Changes in the Level 3 Fair Value Category of Unobservable Inputs (Detail) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2026 |
Sep. 30, 2025 |
Sep. 30, 2026 |
Sep. 30, 2025 |
|
| State and Local Governments Tax-Exempt [Member] | ||||
| Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] | ||||
| Beginning Balance | $ 185 | $ 184 | $ 185 | $ 353 |
| Change in Fair Value | $ 0 | $ 1 | $ 0 | $ 2 |
| Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] | Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent | Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent | Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent | Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent |
| Payments, Maturities & Calls | $ 0 | $ 0 | $ 0 | $ (170) |
| Ending Balance | 185 | 185 | 185 | 185 |
| State and Local Governments Taxable[Member] | ||||
| Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] | ||||
| Beginning Balance | 1,258 | 1,270 | 1,270 | 1,274 |
| Change in Fair Value | $ 2 | $ 3 | $ (10) | $ (1) |
| Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] | Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent | Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent | Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent | Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent |
| Payments, Maturities & Calls | $ 0 | $ 0 | $ 0 | |
| Ending Balance | 1,260 | 1,273 | 1,260 | $ 1,273 |
| State and Local Governments [Member] | ||||
| Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] | ||||
| Beginning Balance | 1,443 | 1,454 | 1,455 | 1,627 |
| Change in Fair Value | $ 2 | $ 4 | $ (10) | $ 1 |
| Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] | Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent | Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent | Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent | Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent |
| Payments, Maturities & Calls | $ 0 | $ 0 | $ 0 | $ (170) |
| Ending Balance | $ 1,445 | $ 1,458 | $ 1,445 | $ 1,458 |