Fair Value - Assets Measured at Fair Value on Recurring Basis (Details) - USD ($)	Jun. 30, 2021	Dec. 31, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities measure at fair value on recurring basis	$ 15,300,000
Available-for-sale securities measure at fair value on recurring basis	283,000	$ 166,000
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	64,127,000	53,070,000
Available-for-sale securities measure at fair value on recurring basis	15,308,000	35,406,000
Available-for-sale securities measure at fair value on recurring basis	283,000	166,000
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	63,844,000	52,904,000
Available-for-sale securities measure at fair value on recurring basis	15,308,000	35,406,000
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	283,000	166,000
Available-for-sale securities measure at fair value on recurring basis	283,000	166,000
U.S. Government 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	2,987,000
U.S. Government 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	2,987,000
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	13,574,000	10,463,000
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	13,574,000	10,463,000
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	15,782,000	3,567,000
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	15,782,000	3,567,000
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	231,000	272,000
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	231,000	272,000
Collateralized Mortgage Obligations | 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	15,962,000
Collateralized Mortgage Obligations | 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	$ 15,962,000
FHLMC 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		3,196,000
FHLMC 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		$ 3,196,000