Loans Receivable, Net - Past Due Financing Receivables (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Mar. 31, 2022
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, gross	$ 597,896	$ 579,504
Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	15,140	11,395
Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	211	200
Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	7,594	11,034
Financial Asset, Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	22,945	22,629
Financial Asset, Not Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	574,951	556,875
One-to-four family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, gross	65,808	70,261
One-to-four family | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	1,207	1,943
One-to-four family | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	185	0
One-to-four family | Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	2,475	5,229
One-to-four family | Financial Asset, Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	3,867	7,172
One-to-four family | Financial Asset, Not Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	61,941	63,089
Multifamily
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, gross	179,117	162,261
Multifamily | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	1,458	4,435
Multifamily | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	0	115
Multifamily | Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	71	515
Multifamily | Financial Asset, Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	1,529	5,065
Multifamily | Financial Asset, Not Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	177,588	157,196
Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, gross	178,424	175,313
Commercial real estate | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	1,370	4,010
Commercial real estate | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	0	0
Commercial real estate | Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	0	4,601
Commercial real estate | Financial Asset, Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	1,370	8,611
Commercial real estate | Financial Asset, Not Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	177,054	166,702
Business
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, gross	166,908	170,031
Business | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	11,006	923
Business | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	0	40
Business | Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	5,014	664
Business | Financial Asset, Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	16,020	1,627
Business | Financial Asset, Not Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	150,888	168,404
Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, gross	7,639	1,638
Consumer | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	99	84
Consumer | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	26	45
Consumer | Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	34	25
Consumer | Financial Asset, Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	159	154
Consumer | Financial Asset, Not Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 7,480	$ 1,484