Loans Receivable and Allowance for Loan and Lease Losses Loans Receivable and ALLL (Details) - USD ($) $ in Thousands		Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Receivable, before Fees, Gross		$ 427,976		$ 474,197
Unamortized premiums, deferred costs and fees, net		3,393		3,556
Allowance for loan losses		(4,792)	$ (5,187)	(5,126)	$ (5,126)	$ (5,133)	$ (5,060)
Total loans receivable, net		$ 426,577		$ 472,627
Percentage of Loan Type		100.00%		100.00%
One-to-four family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Receivable, before Fees, Gross		$ 113,142		$ 121,233
Allowance for loan losses		$ (1,481)	(1,853)	$ (1,210)	(1,179)	(1,518)	(1,663)
Percentage of Loan Type		26.40%		25.60%
Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Receivable, before Fees, Gross		$ 88,877		$ 103,887
Allowance for loan losses		$ (939)	(1,387)	$ (1,819)	(1,369)	(1,227)	(1,213)
Percentage of Loan Type		20.80%		21.90%
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Receivable, before Fees, Gross		$ 122,865		$ 141,835
Allowance for loan losses		$ (702)	(540)	$ (1,052)	(1,692)	(1,647)	(1,496)
Percentage of Loan Type		28.70%		29.90%
Business
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Receivable, before Fees, Gross	[1]	$ 98,504		$ 102,004
Allowance for loan losses		$ (1,530)	(1,169)	$ (1,003)	(832)	(724)	(573)
Percentage of Loan Type	[1]	23.00%		21.50%
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Receivable, before Fees, Gross	[2]	$ 4,588		$ 5,238
Allowance for loan losses		$ (140)	$ (172)	$ (18)	$ (20)	$ (17)	$ (9)
Percentage of Loan Type	[2]	1.10%		1.10%

[1] (1) Includes business overdrafts

[2] 2) Includes personal loans and consumer overdrafts