LOANS AND SERVICING - Summary of loans (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Summary of loans:
Loans receivable	$ 279,492	$ 256,014
Other items:
Net deferred loan costs	484	377
Allowance for loan losses	(2,605)	(2,408)	$ (2,229)
Total loans, net	277,371	253,983
Residential loans:
Summary of loans:
Loans receivable	106,069	104,735
One- to four- family, residential loans
Summary of loans:
Loans receivable	90,190	86,472
Other items:
Allowance for loan losses	(171)	(197)	(273)
Home equity loans and lines of credit
Summary of loans:
Loans receivable	15,879	18,263
Other items:
Allowance for loan losses	(238)	(276)	(249)
Commercial loans:
Summary of loans:
Loans receivable	148,087	130,664
One-to-four family investment property
Summary of loans:
Loans receivable	13,081	15,255
Other items:
Allowance for loan losses	(79)	(90)	(46)
Multi-family real estate
Summary of loans:
Loans receivable	30,748	30,709
Other items:
Allowance for loan losses	(234)	(233)	(113)
Commercial real estate
Summary of loans:
Loans receivable	83,583	67,152
Other items:
Allowance for loan losses	(1,262)	(1,021)	(943)
Commercial business loan
Summary of loans:
Loans receivable	20,675	17,548
Other items:
Allowance for loan losses	(364)	(305)	(311)
Construction loans
Summary of loans:
Loans receivable	25,154	20,378
One-to-four family, construction loans
Summary of loans:
Loans receivable	12,599	12,967
Other items:
Allowance for loan losses	(104)	(113)	(117)
Multi-family
Summary of loans:
Loans receivable	5,725	1,486
Other items:
Allowance for loan losses	(47)	(12)	(97)
Non-residential
Summary of loans:
Loans receivable	6,830	5,925
Other items:
Allowance for loan losses	(104)	(91)	(77)
Consumer
Summary of loans:
Loans receivable	182	237
Other items:
Allowance for loan losses	$ (2)	$ (2)	$ (3)