ALLOWANCE FOR LOAN LOSSES, Impaired Real Estate Loans (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Unpaid Principal Balance [Abstract]
With no related allowance recorded		$ 8,815		$ 5,690
With related allowance recorded		232		309
Total		9,047		5,999
Recorded Investment [Abstract]
With no related allowance recorded	[1]	8,815		5,690
With related allowance recorded	[1]	232		309
Total	[1]	9,047		5,999
Related Allowance [Abstract]
Related allowance		116		230
Average Recorded Investment [Abstract]
With no related allowance recorded	[1]	7,252	$ 8,174
Total	[1]	7,523	8,763
Interest Income Recognized [Abstract]
With no related allowance recorded		112	88
Total		118	88
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		12		14
Recorded Investment [Abstract]
With no related allowance recorded	[1]	12		14
Related Allowance [Abstract]
Related allowance		0		0
Average Recorded Investment [Abstract]
With no related allowance recorded	[1]	13	21
Interest Income Recognized [Abstract]
With no related allowance recorded		0	0
Real Estate Loans [Member] | Multifamily Residential and Residential Mixed-Use [Member]
Unpaid Principal Balance [Abstract]
With no related allowance recorded		537		551
Recorded Investment [Abstract]
With no related allowance recorded	[1]	537		551
Related Allowance [Abstract]
Related allowance		0		0
Average Recorded Investment [Abstract]
With no related allowance recorded	[1]	544	611
Interest Income Recognized [Abstract]
With no related allowance recorded		13	12
Real Estate Loans [Member] | Commercial Real Estate and Commercial Mixed-Use [Member]
Unpaid Principal Balance [Abstract]
With no related allowance recorded		8,266		5,125
Recorded Investment [Abstract]
With no related allowance recorded	[1]	8,266		5,125
Related Allowance [Abstract]
Related allowance		0		0
Average Recorded Investment [Abstract]
With no related allowance recorded	[1]	6,695	7,542
Interest Income Recognized [Abstract]
With no related allowance recorded		99	76
C & I [Member]
Unpaid Principal Balance [Abstract]
With related allowance recorded		232		309
Recorded Investment [Abstract]
With related allowance recorded	[1]	232		309
Related Allowance [Abstract]
Related allowance		116		$ 230
Average Recorded Investment [Abstract]
With an allowance recorded	[1]	271	589
Interest Income Recognized [Abstract]
With an allowance recorded		$ 6	$ 0

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