Loans Receivable and ALLL (Details) - USD ($) $ in Thousands		Dec. 31, 2021	Sep. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Mar. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Receivable, before Fees, Gross		$ 550,081		$ 480,470
Unamortized premiums, deferred costs and fees, net		2,796		3,079
Allowance for loan and lease losses		(5,488)	$ (5,515)	(5,140)	$ (5,138)	$ (4,916)	$ (4,946)
Total loans receivable, net		$ 547,389		$ 478,409
Percentage of Loan Type		100.00%		100.00%
Other Real Estate Owned		$ 60		$ 60
Financing Receivable, Troubled Debt Restructuring		7,300		7,500
One-to-four family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Receivable, before Fees, Gross		71,356		76,313
Allowance for loan and lease losses		$ (921)	(1,015)	$ (1,058)	(864)	(953)	(1,055)
Percentage of Loan Type		13.00%		15.90%
Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Receivable, before Fees, Gross		$ 152,743		$ 103,584
Allowance for loan and lease losses		$ (1,102)	(914)	$ (880)	(1,027)	(960)	(1,011)
Percentage of Loan Type		27.80%		21.60%
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Receivable, before Fees, Gross		$ 165,050		$ 150,114
Allowance for loan and lease losses		$ (1,095)	(1,002)	$ (907)	(966)	(969)	(812)
Percentage of Loan Type		30.00%		31.20%
Business
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Receivable, before Fees, Gross	[1]	$ 159,214		$ 148,020
Allowance for loan and lease losses		$ (2,108)	(2,106)	$ (1,855)	(1,838)	(1,636)	(1,567)
Percentage of Loan Type	[1]	28.90%		30.80%
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Receivable, before Fees, Gross	[2]	$ 1,718		$ 2,439
Allowance for loan and lease losses		$ (131)	$ (137)	$ (165)	$ (190)	$ (189)	$ (212)
Percentage of Loan Type	[2]	0.30%		0.50%

[1] (1) Includes PPP loans and business overdrafts

[2] 2) Includes personal loans and consumer overdrafts