Credit Quality Indicators (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Mar. 31, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	$ 458,571	$ 428,732
Multifamily
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	92,125	89,887
Multifamily | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	91,752	89,512
Multifamily | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	0	0
Multifamily | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	373	375
Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	148,786	142,410
Commercial real estate | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	143,260	141,793
Commercial real estate | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	1,387	617
Commercial real estate | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	4,139	0
Business
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	116,678	85,659
Business | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	111,758	80,016
Business | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	1,630	2,184
Business | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	3,290	3,459
One-to-four family
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	97,976	107,528
One-to-four family | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	94,305	103,946
One-to-four family | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	3,671	3,582
Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	3,006	3,248
Consumer | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	3,006	3,225
Consumer | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	$ 0	$ 23