Fair Value Measurement and Fair Value of Financial Instruments - Fair Value of Financial Assets and Liabilities Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Assets:
Total	$ 942,510	$ 1,054,312
Equity securities, at fair value	17,207	17,283
U.S. government agencies
Assets:
Total	320,888	355,639
Mortgage-backed securities, multifamily
Assets:
Total	640	785
Asset-backed securities
Assets:
Total	45,824	52,395
Obligations of states and political subdivisions
Assets:
Total	19,002	21,122
Corporate bonds
Assets:
Total	94,704	113,367
Fair Value, Measurements, Recurring
Assets:
Total	942,510	1,054,312
Equity securities, at fair value	17,207	17,283
Derivative assets	122,286	97,848
Total Assets	1,082,003	1,169,443
Liabilities:
Derivative liabilities	122,290	97,848
Total Liabilities	122,290	97,848
Fair Value, Measurements, Recurring | U.S. government agencies
Assets:
Total	320,888	355,639
Fair Value, Measurements, Recurring | Mortgage-backed securities, residential
Assets:
Total	279,283	310,613
Fair Value, Measurements, Recurring | Collateralized mortgage obligations, residential
Assets:
Total	138,033	154,058
Fair Value, Measurements, Recurring | Mortgage-backed securities, multifamily
Assets:
Total	640	785
Fair Value, Measurements, Recurring | Collateralized mortgage obligations, multifamily
Assets:
Total	44,136	46,333
Fair Value, Measurements, Recurring | Asset-backed securities
Assets:
Total	45,824	52,395
Fair Value, Measurements, Recurring | Obligations of states and political subdivisions
Assets:
Total	19,002	21,122
Fair Value, Measurements, Recurring | Corporate bonds
Assets:
Total	94,704	113,367
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Measurements, Recurring
Assets:
Total	143,474	162,438
Equity securities, at fair value	0	0
Derivative assets	0	0
Total Assets	143,474	162,438
Liabilities:
Derivative liabilities	0	0
Total Liabilities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Measurements, Recurring | U.S. government agencies
Assets:
Total	143,474	162,438
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Mortgage-backed securities, residential
Assets:
Total	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Collateralized mortgage obligations, residential
Assets:
Total	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Mortgage-backed securities, multifamily
Assets:
Total	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Collateralized mortgage obligations, multifamily
Assets:
Total	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Asset-backed securities
Assets:
Total	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Obligations of states and political subdivisions
Assets:
Total	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Corporate bonds
Assets:
Total	0	0
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring
Assets:
Total	799,036	891,874
Equity securities, at fair value	17,207	17,283
Derivative assets	122,286	97,848
Total Assets	938,529	1,007,005
Liabilities:
Derivative liabilities	122,290	97,848
Total Liabilities	122,290	97,848
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | U.S. government agencies
Assets:
Total	177,414	193,201
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Mortgage-backed securities, residential
Assets:
Total	279,283	310,613
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Collateralized mortgage obligations, residential
Assets:
Total	138,033	154,058
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Mortgage-backed securities, multifamily
Assets:
Total	640	785
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Collateralized mortgage obligations, multifamily
Assets:
Total	44,136	46,333
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Asset-backed securities
Assets:
Total	45,824	52,395
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Obligations of states and political subdivisions
Assets:
Total	19,002	21,122
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Corporate bonds
Assets:
Total	94,704	113,367
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring
Assets:
Total	0	0
Equity securities, at fair value	0	0
Derivative assets	0	0
Total Assets	0	0
Liabilities:
Derivative liabilities	0	0
Total Liabilities	0	0
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring | U.S. government agencies
Assets:
Total	0	0
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring | Mortgage-backed securities, residential
Assets:
Total	0	0
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring | Collateralized mortgage obligations, residential
Assets:
Total	0	0
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring | Mortgage-backed securities, multifamily
Assets:
Total	0	0
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring | Collateralized mortgage obligations, multifamily
Assets:
Total	0	0
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring | Asset-backed securities
Assets:
Total	0	0
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring | Obligations of states and political subdivisions
Assets:
Total	0	0
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring | Corporate bonds
Assets:
Total	$ 0	$ 0