Nonaccrual Loans (Details) - Nonperforming - USD ($) $ in Thousands	Sep. 30, 2021	Mar. 31, 2021
Financing Receivable, Past Due [Line Items]
Financing Receivable, Nonaccrual	$ 6,722	$ 7,191
One-to-four family
Financing Receivable, Past Due [Line Items]
Financing Receivable, Nonaccrual	3,500	3,524
Multifamily
Financing Receivable, Past Due [Line Items]
Financing Receivable, Nonaccrual	882	369
Commercial real estate
Financing Receivable, Past Due [Line Items]
Financing Receivable, Nonaccrual	192	918
Business
Financing Receivable, Past Due [Line Items]
Financing Receivable, Nonaccrual	2,148	2,290
Consumer
Financing Receivable, Past Due [Line Items]
Financing Receivable, Nonaccrual	$ 0	$ 90