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Derivative Financial Instruments - Information about Interest Rate Swap Agreements (Detail) - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2025 | Dec. 31, 2024
Derivative [Line Items] |  |
Notional Amount | $ 32,819,000 | $ 36,184,000
Average Maturity (in years) | 2 years 2 months 12 days | 2 years 2 months 12 days
Estimated fair value gain (loss) | $ 12,000 | $ (1,000)
Fair value hedges: |  |
Derivative [Line Items] |  |
Impact of estimated fair value gain (losses) on hedging instruments | 71,000 | (153,000)
Cash flow hedges: |  |
Derivative [Line Items] |  |
Impact of estimated fair value gain (losses) on hedging instruments | (6,000) | (136,000)
Interest Payments On Variable Rate Commercial Real Estate Loans | Cash flow hedges: |  |
Derivative [Line Items] |  |
Notional Amount | $ 27,469,000 | $ 30,819,000
Average Maturity (in years) | 1 year 6 months | 1 year 7 months 6 days
Fixed | 3.54% | 3.41%
Variable | 4.33% | 4.47%
Estimated fair value gain (loss) | $ 3,000 | $ 1,000
Fixed Rate Long-Term Borrowings | Fair value hedges: |  |
Derivative [Line Items] |  |
Notional Amount | $ 5,350,000 | $ 5,350,000
Average Maturity (in years) | 5 years 7 months 6 days | 5 years 10 months 24 days
Fixed | 3.55% | 3.55%
Variable | 4.43% | 4.71%
Estimated fair value gain (loss) | $ 9,000 | $ (2,000)
Fixed Rate Available For Sale Securities | Fair value hedges: |  |
Derivative [Line Items] |  |
Notional Amount |  | $ 15,000
Average Maturity (in years) |  | 1 month 6 days
Fixed |  | 4.84%
Variable |  | 4.36%
Estimated fair value gain (loss) |  | $ 0

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