Fair Value of Financial Instruments - Impaired Loans (Detail) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Level 3 [Member] | Collateral Dependent Impaired Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value on a nonrecurring basis, Total	$ 7,516	$ 7,703
Other Real Estate Owned-Residential [Member] | Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value on a nonrecurring basis, Total	137
Fair Value on Nonrecurring Basis [Member] | Collateral Dependent Impaired Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value on a nonrecurring basis, Total	7,516	7,703
Fair Value on Nonrecurring Basis [Member] | Level 3 [Member] | Collateral Dependent Impaired Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value on a nonrecurring basis, Total	7,516	$ 7,703
Fair Value on Nonrecurring Basis [Member] | Other Real Estate Owned-Residential [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value on a nonrecurring basis, Total	137
Fair Value on Nonrecurring Basis [Member] | Other Real Estate Owned-Residential [Member] | Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value on a nonrecurring basis, Total	$ 137