Impaired Loans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Mar. 31, 2021
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, Recorded Investment	$ 13,245		$ 13,245		$ 12,868
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, Unpaid Principal Balance	13,904		13,904		13,718
Impaired Financing Receivable, Related Allowance	112		112		158
Impaired Financing Receivable, Average Recorded Investment [Abstract]
Impaired Financing Receivable, Average Recorded Investment	12,807	$ 10,876	13,055	$ 10,827
Impaired Financing Receivable, Interest Income, Cash Basis Method [Abstract]
Impaired Financing Receivable, Interest Income, Cash Basis Method	53	40	209	149
One-to-four family
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	5,137		5,137		3,750
Impaired Financing Receivable, with Related Allowance, Recorded Investment	73		73		76
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	5,796		5,796		4,409
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	73		73		72
Impaired Financing Receivable, Related Allowance	29		29		32
Impaired Financing Receivable, Average Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	4,429	3,790	4,443	3,767
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	73	442	74	77
Impaired Financing Receivable, Interest Income, Cash Basis Method [Abstract]
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	13	10	19	50
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	0	0	1	0
Multifamily
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	516		516		369
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	516		516		369
Impaired Financing Receivable, Average Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	699	373	442	371
Impaired Financing Receivable, Interest Income, Cash Basis Method [Abstract]
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	9	4	9	13
Commercial real estate
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	185		185		918
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	185		185		918
Impaired Financing Receivable, Average Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	188	580	551	1,160
Impaired Financing Receivable, Interest Income, Cash Basis Method [Abstract]
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	7	0	7	0
Business
Impaired Financing Receivable, Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	2,091		2,091		2,332
Impaired Financing Receivable, with Related Allowance, Recorded Investment	5,243		5,243		5,423
Impaired Financing Receivable, Unpaid Principal Balance [Abstract]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	2,091		2,091		2,527
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	5,243		5,243		5,423
Impaired Financing Receivable, Related Allowance	83		83		$ 126
Impaired Financing Receivable, Average Recorded Investment [Abstract]
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	2,125	2,634	2,212	2,445
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	5,293	3,057	5,333	3,007
Impaired Financing Receivable, Interest Income, Cash Basis Method [Abstract]
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	24	26	24	86
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	$ 0	$ 0	$ 149	$ 0