Fair Value - Assets Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities measure at fair value on recurring basis	$ 58
Fair Value Measurement Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities measure at fair value on recurring basis	27,670	$ 21,504
Available-for-sale securities measure at fair value on recurring basis	13,100
Available-for-sale securities measure at fair value on recurring basis	58
Fair Value Measurement Recurring | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities measure at fair value on recurring basis	27,612	21,504
Available-for-sale securities measure at fair value on recurring basis	13,100
Fair Value Measurement Recurring | Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities measure at fair value on recurring basis	58
Available-for-sale securities measure at fair value on recurring basis	58
U.S. Government and Federal Agencies | Fair Value Measurement Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities measure at fair value on recurring basis		16,354
U.S. Government and Federal Agencies | Fair Value Measurement Recurring | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities measure at fair value on recurring basis		16,354
Corporate Bonds | Fair Value Measurement Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities measure at fair value on recurring basis	10,233
Corporate Bonds | Fair Value Measurement Recurring | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities measure at fair value on recurring basis	10,233
FNMA Certificates | Fair Value Measurement Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities measure at fair value on recurring basis	3,981	4,659
FNMA Certificates | Fair Value Measurement Recurring | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities measure at fair value on recurring basis	3,981	4,659
GNMA Certificates | Fair Value Measurement Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities measure at fair value on recurring basis	298	491
GNMA Certificates | Fair Value Measurement Recurring | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities measure at fair value on recurring basis	$ 298	$ 491