Loans Receivable and Allowance for Loan Losses - Financing Receivable Credit Quality Indicators (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	$ 359,543	$ 339,708
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	356,278	336,136
Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	1,548	1,367
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	1,717	1,717
Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	0	0
Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	0	0
Commercial and multi-family real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	227,097	212,290
Commercial and multi-family real estate | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	223,975	209,206
Commercial and multi-family real estate | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	1,490	1,367
Commercial and multi-family real estate | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	1,632	1,717
Commercial and multi-family real estate | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	0	0
Commercial and multi-family real estate | Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	0	0
Construction
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	31,465	18,905
Construction | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	31,465	18,905
Construction | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	0	0
Construction | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	0	0
Construction | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	0	0
Construction | Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	0	0
Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	100,981	108,513
Commercial and industrial | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	100,838	108,025
Commercial and industrial | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	58	69
Commercial and industrial | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	85	419
Commercial and industrial | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	0	0
Commercial and industrial | Loss
Financing Receivable, Credit Quality Indicator [Line Items]
Loans receivable	$ 0	$ 0