Loans Receivable and ALLL (Details) - USD ($) $ in Thousands		Dec. 31, 2019	Sep. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Mar. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Receivable, before Fees, Gross		$ 418,803		$ 425,805
Unamortized premiums, deferred costs and fees, net		3,516		3,023
Allowance for loan losses		(4,607)	$ (4,625)	(4,646)	$ (4,802)	$ (4,792)	$ (5,126)
Total loans receivable, net		$ 417,712		$ 424,182
Percentage of Loan Type		100.00%		100.00%
Other Real Estate Owned		$ 120		$ 404
Financing Receivable, Troubled Debt Restructuring		4,300		5,400
One-to-four family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Receivable, before Fees, Gross		111,218		108,363
Allowance for loan losses		$ (1,181)	(1,289)	$ (1,274)	(1,463)	(1,481)	(1,210)
Percentage of Loan Type		26.60%		25.50%
Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Receivable, before Fees, Gross		$ 83,503		$ 86,177
Allowance for loan losses		$ (920)	(884)	$ (885)	(874)	(939)	(1,819)
Percentage of Loan Type		19.90%		20.20%
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Receivable, before Fees, Gross		$ 134,884		$ 130,812
Allowance for loan losses		$ (691)	(695)	$ (766)	(738)	(702)	(1,052)
Percentage of Loan Type		32.20%		30.70%
Business
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Receivable, before Fees, Gross	[1]	$ 85,646		$ 96,430
Allowance for loan losses		$ (1,484)	(1,491)	$ (1,330)	(1,378)	(1,530)	(1,003)
Percentage of Loan Type	[1]	20.50%		22.70%
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Receivable, before Fees, Gross	[2]	$ 3,552		$ 4,023
Allowance for loan losses		$ (231)	$ (248)	$ (154)	$ (122)	$ (140)	$ (18)
Percentage of Loan Type	[2]	0.80%		0.90%

[1] ⁽¹⁾ Includes business overdrafts

[2] 2) Includes personal loans and consumer overdrafts