Credit Risk Ratings by Loan Segment (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Financing Receivable Recorded Investment [Line Items]
Loans before net deferred loan origination cost and allowance for losses on loan	$ 777,835	$ 651,642
1-4 Family
Financing Receivable Recorded Investment [Line Items]
Loans before net deferred loan origination cost and allowance for losses on loan	378,936	325,040
Multifamily
Financing Receivable Recorded Investment [Line Items]
Loans before net deferred loan origination cost and allowance for losses on loan	177,181	158,200
Nonresidential
Financing Receivable Recorded Investment [Line Items]
Loans before net deferred loan origination cost and allowance for losses on loan	152,692	121,500
Construction and Land
Financing Receivable Recorded Investment [Line Items]
Loans before net deferred loan origination cost and allowance for losses on loan	52,483	30,340
Business
Financing Receivable Recorded Investment [Line Items]
Loans before net deferred loan origination cost and allowance for losses on loan	15,600	15,719
Consumer
Financing Receivable Recorded Investment [Line Items]
Loans before net deferred loan origination cost and allowance for losses on loan	943	843
Pass
Financing Receivable Recorded Investment [Line Items]
Loans before net deferred loan origination cost and allowance for losses on loan	750,354	629,868
Pass | 1-4 Family
Financing Receivable Recorded Investment [Line Items]
Loans before net deferred loan origination cost and allowance for losses on loan	362,900	313,345
Pass | Multifamily
Financing Receivable Recorded Investment [Line Items]
Loans before net deferred loan origination cost and allowance for losses on loan	176,644	158,200
Pass | Nonresidential
Financing Receivable Recorded Investment [Line Items]
Loans before net deferred loan origination cost and allowance for losses on loan	150,479	117,467
Pass | Construction and Land
Financing Receivable Recorded Investment [Line Items]
Loans before net deferred loan origination cost and allowance for losses on loan	45,210	24,316
Pass | Business
Financing Receivable Recorded Investment [Line Items]
Loans before net deferred loan origination cost and allowance for losses on loan	14,178	15,697
Pass | Consumer
Financing Receivable Recorded Investment [Line Items]
Loans before net deferred loan origination cost and allowance for losses on loan	943	843
Special Mention
Financing Receivable Recorded Investment [Line Items]
Loans before net deferred loan origination cost and allowance for losses on loan	6,583	2,549
Special Mention | 1-4 Family
Financing Receivable Recorded Investment [Line Items]
Loans before net deferred loan origination cost and allowance for losses on loan	3,833	2,549
Special Mention | Multifamily
Financing Receivable Recorded Investment [Line Items]
Loans before net deferred loan origination cost and allowance for losses on loan	537
Special Mention | Nonresidential
Financing Receivable Recorded Investment [Line Items]
Loans before net deferred loan origination cost and allowance for losses on loan	207
Special Mention | Construction and Land
Financing Receivable Recorded Investment [Line Items]
Loans before net deferred loan origination cost and allowance for losses on loan	597
Special Mention | Business
Financing Receivable Recorded Investment [Line Items]
Loans before net deferred loan origination cost and allowance for losses on loan	1,409
Substandard
Financing Receivable Recorded Investment [Line Items]
Loans before net deferred loan origination cost and allowance for losses on loan	20,898	19,225
Substandard | 1-4 Family
Financing Receivable Recorded Investment [Line Items]
Loans before net deferred loan origination cost and allowance for losses on loan	12,203	9,146
Substandard | Nonresidential
Financing Receivable Recorded Investment [Line Items]
Loans before net deferred loan origination cost and allowance for losses on loan	2,006	4,033
Substandard | Construction and Land
Financing Receivable Recorded Investment [Line Items]
Loans before net deferred loan origination cost and allowance for losses on loan	6,676	6,024
Substandard | Business
Financing Receivable Recorded Investment [Line Items]
Loans before net deferred loan origination cost and allowance for losses on loan	$ 13	$ 22