Loans Receivable - Analysis of collateral-dependent loans (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Mar. 31, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total collateral-dependent loans	$ 2,162	$ 2,505
One- to four-family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total collateral-dependent loans	1,617	1,977
Real estate - nonresidential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total collateral-dependent loans	29	29
Commercial business
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total collateral-dependent loans	412
Home equity and junior liens
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total collateral-dependent loans	104
Residential Properties
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total collateral-dependent loans	1,750	2,091
Residential Properties | One- to four-family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total collateral-dependent loans	1,617	1,977
Residential Properties | Real estate - nonresidential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total collateral-dependent loans	29	29
Residential Properties | Home equity and junior liens
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total collateral-dependent loans	104
Business Assets
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total collateral-dependent loans	412	$ 414
Business Assets | Commercial business
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total collateral-dependent loans	$ 412