INVESTMENT AND MORTGAGE-BACKED SECURITIES, Major Categories of Securities Owned (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Securities, available-for-sale [Abstract]
Amortized Cost	$ 511,565		$ 511,565		$ 505,786
Gross Unrealized Gains	8,125		8,125		776
Gross Unrealized Losses	(82)		(82)		(3,677)
Fair Value	519,608		519,608		502,885
Securities pledged as collateral	27,728		27,728		27,248
Available-for-sale Agency Securities [Abstract]
Proceeds			130,504	$ 158,758
Proceeds [Abstract]
Marketable equity securities			434	923
Net gains on securities			430	110
Marketable Equity Securities [Member]
Proceeds [Abstract]
Marketable equity securities	161	$ 394	434	923
Net gains on securities	14	94	430	110
Agency Notes [Member]
Securities, available-for-sale [Abstract]
Amortized Cost	40,000		40,000		25,110
Gross Unrealized Gains	47		47		45
Gross Unrealized Losses	0		0		(10)
Fair Value	40,047		$ 40,047		25,145
Investment and Mortgage-Backed Securities [Abstract]
Securities weighted average term to maturity			6 years 7 months 6 days
Corporate Securities [Member]
Securities, available-for-sale [Abstract]
Amortized Cost	26,102		$ 26,102		11,167
Gross Unrealized Gains	441		441		0
Gross Unrealized Losses	0		0		(32)
Fair Value	26,543		$ 26,543		11,135
Investment and Mortgage-Backed Securities [Abstract]
Securities weighted average term to maturity			5 years 8 months 12 days
Available-for-sale Agency Securities [Abstract]
Proceeds	0	0	$ 3,038	0
Gross gains	0	0	39	0
Tax expense on gain	0	0	12	0
Gross losses	0	0	0	0
Tax benefit on loss	0	0	0	0
Pass-through MBS Issued by GSEs [Member]
Securities, available-for-sale [Abstract]
Amortized Cost	241,616		241,616		356,039
Gross Unrealized Gains	5,822		5,822		574
Gross Unrealized Losses	(7)		(7)		(2,000)
Fair Value	247,431		$ 247,431		354,613
Investment and Mortgage-Backed Securities [Abstract]
Securities weighted average term to maturity			16 years 2 months 12 days
Available-for-sale Agency Securities [Abstract]
Proceeds	15,149	274	$ 106,860	274
Gross gains	22	4	270	4
Tax expense on gain	7	1	86	1
Gross losses	2	0	520	0
Tax benefit on loss	0	0	166	0
Agency CMOs [Member]
Securities, available-for-sale [Abstract]
Amortized Cost	203,847		203,847		113,470
Gross Unrealized Gains	1,815		1,815		157
Gross Unrealized Losses	(75)		(75)		(1,635)
Fair Value	205,587		$ 205,587		$ 111,992
Investment and Mortgage-Backed Securities [Abstract]
Securities weighted average term to maturity			16 years 2 months 12 days
Available-for-sale Agency Securities [Abstract]
Proceeds	11,224	0	$ 20,606	158,484
Gross gains	46	0	144	1,370
Tax expense on gain	15	0	46	440
Gross losses	0	0	0	0
Tax benefit on loss	$ 0	$ 0	$ 0	$ 0

Refers to the amount of income tax benefit related to loss on sale of mortgage backed securities.

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Refers to the amount of income tax expenses related to gain on sale of mortgage backed securities.

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The weighted average term to maturity.

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Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of realized gain on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of realized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of realized gain (loss) from sale of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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The cash inflow associated with the aggregate amount received by the entity through sale or maturity of marketable securities (held-to-maturity or available-for-sale) during the period.

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Amount of cash inflow from sale of investment in mortgage-backed security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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