Loans Receivable and Allowance for Loan and Lease Losses Nonaccrual Loans (Details) - Nonperforming - USD ($) $ in Thousands	Jun. 30, 2017	Mar. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	$ 8,707	$ 8,418
One-to-four family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	4,703	3,899
Multifamily
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	1,589	1,602
Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	1,389	993
Business
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	1,026	1,922
Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	$ 0	$ 2