ALLOWANCE FOR LOAN LOSSES, Impaired Real Estate Loans (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018		Mar. 31, 2017		Dec. 31, 2017
Unpaid Principal Balance [Abstract]
With an allowance recorded		$ 1,179				$ 0
Total		9,324				8,204
Recorded Investment [Abstract]
With an allowance recorded	[1]	1,179				0
Total	[1]	9,324				8,204
Related Allowance [Abstract]
Related allowance		294				0
Average Recorded Investment [Abstract]
Total		8,763	[1]	$ 11,834	[2]
Interest Income Recognized [Abstract]
Total		88		132
Real Estate Loans [Member]
Unpaid Principal Balance [Abstract]
With no related allowance recorded		8,145				8,204
Recorded Investment [Abstract]
With no related allowance recorded	[1]	8,145				8,204
Related Allowance [Abstract]
Related allowance		0				0
Average Recorded Investment [Abstract]
With no related allowance recorded	[1]	8,174		11,834
Interest Income Recognized [Abstract]
With no related allowance recorded		88		132
Real Estate Loans [Member] | One- to Four-Family Residential, Including Condominium and Cooperative Apartment [Member]
Unpaid Principal Balance [Abstract]
With no related allowance recorded		20				22
Recorded Investment [Abstract]
With no related allowance recorded	[1]	20				22
Related Allowance [Abstract]
Related allowance		0				0
Average Recorded Investment [Abstract]
With no related allowance recorded	[1]	21		404
Interest Income Recognized [Abstract]
With no related allowance recorded		0		7
Real Estate Loans [Member] | Multifamily Residential And Residential Mixed Use Allowance [Member]
Unpaid Principal Balance [Abstract]
With no related allowance recorded		604				619
Recorded Investment [Abstract]
With no related allowance recorded	[1]	604				619
Related Allowance [Abstract]
Related allowance		0				0
Average Recorded Investment [Abstract]
With no related allowance recorded	[1]	611		3,302
Interest Income Recognized [Abstract]
With no related allowance recorded		12		46
Real Estate Loans [Member] | Commercial Mixed Use Real Estate [Member]
Unpaid Principal Balance [Abstract]
With no related allowance recorded		4,242				4,267
Recorded Investment [Abstract]
With no related allowance recorded	[1]	4,242				4,267
Related Allowance [Abstract]
Related allowance		0				0
Average Recorded Investment [Abstract]
With no related allowance recorded	[1]	4,255		4,773
Interest Income Recognized [Abstract]
With no related allowance recorded		43		45
Real Estate Loans [Member] | Commercial Real Estate [Member]
Unpaid Principal Balance [Abstract]
With no related allowance recorded		3,279				3,296
Recorded Investment [Abstract]
With no related allowance recorded	[1]	3,279				3,296
Related Allowance [Abstract]
Related allowance		0				0
Average Recorded Investment [Abstract]
With no related allowance recorded	[1]	3,287		3,355
Interest Income Recognized [Abstract]
With no related allowance recorded		33		34
C & I [Member]
Unpaid Principal Balance [Abstract]
With an allowance recorded		1,179				0
Recorded Investment [Abstract]
With an allowance recorded	[1]	1,179				0
Related Allowance [Abstract]
Related allowance		294				$ 0
Average Recorded Investment [Abstract]
With an allowance recorded		589	[1]	0	[2]
Interest Income Recognized [Abstract]
With an allowance recorded		$ 0		$ 0

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

[2] Amount recognized as a component of mortgage banking income during the period.