Loans Receivable, Net - Credit Quality Indicators(Details) - USD ($) $ in Thousands	Mar. 31, 2018	Mar. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	$ 477,753	$ 545,552
Multifamily
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	104,865	88,750
Multifamily | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	103,160	87,148
Multifamily | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	0	0
Multifamily | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	1,705	1,082
Multifamily | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	0	520
Multifamily | Loss
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	0	0
Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	142,304	242,818
Commercial real estate | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	140,765	238,552
Commercial real estate | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	0	771
Commercial real estate | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	1,539	3,495
Commercial real estate | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	0	0
Commercial real estate | Loss
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	0	0
Construction
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	0	4,949
Construction | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	0	4,949
Construction | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	0	0
Construction | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	0	0
Construction | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	0	0
Construction | Loss
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	0	0
Business
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	102,203	65,114
Business | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	93,886	58,555
Business | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	5,028	133
Business | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	3,289	6,426
Business | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	0	0
Business | Loss
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	0	0
One-to-four family
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	123,092	134,927
One-to-four family | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	116,588	131,028
One-to-four family | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	6,504	3,899
Consumer
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	5,289	8,994
Consumer | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	5,289	8,992
Consumer | Non-performing
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	$ 0	$ 2