ALLOWANCE FOR LOAN LOSSES, Impaired Real Estate Loans (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018		Dec. 31, 2017	Dec. 31, 2016
Unpaid Principal Balance [Abstract]
With no related allowance recorded		$ 5,690		$ 8,204
With related allowance recorded		309		0
Total		5,999		8,204
Recorded Investment [Abstract]
With no related allowance recorded	[1]	5,690		8,204
With related allowance recorded		309	[1]	0
Total		5,999	[1]	8,204
Related Allowance [Abstract]
Related allowance		230		0
Average Recorded Investment [Abstract]
With no related allowance recorded	[1]	6,992		10,362	$ 10,863
With related allowance recorded	[1]	298		0	0
Total	[1]	7,290		10,362	10,863
Interest Income Recognized [Abstract]
With no related allowance recorded	[2]	402		422	548
With related allowance recorded	[2]	3		0	0
Total	[2]	405		422	548
Real Estate Loans [Member]
Related Allowance [Abstract]
Related allowance		0		0
Real Estate Loans [Member] | One- to Four-Family Residential, Including Condominium and Cooperative Apartment [Member]
Unpaid Principal Balance [Abstract]
With no related allowance recorded		14		22
Recorded Investment [Abstract]
With no related allowance recorded	[1]	14		22
Related Allowance [Abstract]
Related allowance		0		0
Average Recorded Investment [Abstract]
With no related allowance recorded	[1]	18		325	443
Interest Income Recognized [Abstract]
With no related allowance recorded	[2]	0		30	53
Real Estate Loans [Member] | Multifamily Residential and Residential Mixed-Use [Member]
Unpaid Principal Balance [Abstract]
With no related allowance recorded		551		619
Recorded Investment [Abstract]
With no related allowance recorded	[1]	551		619
Related Allowance [Abstract]
Related allowance		0		0
Average Recorded Investment [Abstract]
With no related allowance recorded	[1]	824		2,222	2,515
Interest Income Recognized [Abstract]
With no related allowance recorded	[2]	53		85	183
Real Estate Loans [Member] | Commercial Real Estate and Commercial Mixed-Use [Member]
Unpaid Principal Balance [Abstract]
With no related allowance recorded		5,125		7,563
Recorded Investment [Abstract]
With no related allowance recorded	[1]	5,125		7,563
Related Allowance [Abstract]
Related allowance		0		0
Average Recorded Investment [Abstract]
With no related allowance recorded	[1]	6,150		7,815	7,905
Interest Income Recognized [Abstract]
With no related allowance recorded	[2]	349		307	312
C & I [Member]
Unpaid Principal Balance [Abstract]
With related allowance recorded		309		0
Recorded Investment [Abstract]
With related allowance recorded		309	[1]	0
Related Allowance [Abstract]
Related allowance		230		0
Average Recorded Investment [Abstract]
With related allowance recorded	[1]	298		0	0
Interest Income Recognized [Abstract]
With related allowance recorded	[2]	$ 3		$ 0	$ 0

[1] The recorded investment excludes accrued interest receivable and loan origination fees, net, due to immateriality.

[2] Cash basis interest and interest income recognized on accrual basis approximate each other.