Credit Quality Indicators (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	$ 422,319	$ 428,828
Multifamily
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	84,072	86,886
Multifamily | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	83,694	83,672
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	378	3,214
Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	135,424	131,292
Commercial real estate | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	134,803	128,319
Commercial real estate | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	621	2,497
Commercial real estate | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	0	476
Business
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	85,883	96,661
Business | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	78,458	90,336
Business | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	3,951	2,425
Business | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	3,474	3,900
One-to-four family
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	113,352	109,926
One-to-four family | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	109,299	106,531
One-to-four family | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	4,053	3,395
Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	3,588	4,063
Consumer | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	3,580	4,063
Consumer | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, gross	$ 8	$ 0