Fair Value Measurements (Narrative) (Detail) $ in Thousands	Mar. 31, 2024 USD ($) security	Dec. 31, 2023 USD ($)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Restricted cash	$ 70	$ 70
Held-to-maturity, debt securities	341,459	352,601
Quoted Prices in Active  Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity, debt securities	16,192	15,553
Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity, debt securities	325,267	337,048
Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity, debt securities	0	0
Agency-guaranteed obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity, debt securities	10,425	10,406
Agency-guaranteed obligations | Quoted Prices in Active  Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity, debt securities	10,425	10,406
Agency-guaranteed obligations | Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity, debt securities	0	0
Agency-guaranteed obligations | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity, debt securities	0	0
U.S. Treasury obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity, debt securities	5,767	5,147
U.S. Treasury obligations | Quoted Prices in Active  Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity, debt securities	5,767	5,147
U.S. Treasury obligations | Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity, debt securities	0	0
U.S. Treasury obligations | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity, debt securities	0	0
Carrying value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity, debt securities	354,671	363,080
Carrying value | Agency-guaranteed obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity, debt securities	11,058	11,058
Carrying value | U.S. Treasury obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity, debt securities	5,767	5,146
Fair value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity, debt securities	341,459	352,601
Fair value | Agency-guaranteed obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity, debt securities	10,425	10,406
Fair value | U.S. Treasury obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity, debt securities	$ 5,767	$ 5,147
Minimum | Measurement Input, Cost to Sell | Valuation, Market Approach
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Impaired loans, measurement input | security	0.05
Foreclosed assets, measurement input | security	0.05
Maximum | Measurement Input, Cost to Sell | Valuation, Market Approach
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Impaired loans, measurement input | security	0.10
Foreclosed assets, measurement input | security	0.10