LOANS - Additional Information (Details)	12 Months Ended
	Dec. 31, 2019 USD ($) Loan	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Financing Receivable Recorded Investment Past Due [Line Items]
Loans held for sale, at lower of cost or fair value	$ 14,667,000	$ 3,542,000
Gain (loss) on loans held for sale at lower of cost or fair value	(10,000)	(4,392,000)	$ 412,000
Impaired non-accrual loans	28,881,000	25,715,000
Impaired non-accrual loans performing troubled debt restructured	2,400,000	4,300,000
Allowance allocated to troubled debt restructured loans	2,800,000	262,000
Allowance allocated to non accrual loans	2,700,000	161,000
Loan receivable, validate risk ratings performed for new lending to existing relationships	1,000,000
Loan receivable, validate risk ratings performed for criticized and classified rated borrowers with relationship exposure, value	500,000
Loan receivable, validate risk ratings performed for random sample of borrowers with relationship, value	1,000,000
Loan receivable, validate risk ratings performed for new regulation "O" loan commitments, value	1,000,000
Loan receivable validate risk ratings performed for leveraged loans, value	1,000,000
Loan receivable validate risk ratings performed for no borrower with commitments, value	250,000
Troubled debt restructurings specific reserves to customers	2,800,000	262,000
Substandard [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Financing receivable impaired loan	$ 35,900,000	31,200,000
Multifamily Property [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans held for sale, at lower of cost or fair value		$ 131,300,000
Multifamily Property [Member] | Residential Portfolio Segment [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Loans held for sale, at lower of cost or fair value			$ 109,900,000
Commercial and Industrial Sector [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Number of loan sold | Loan	1
Loans held for sale, at lower of cost or fair value	$ 5,000,000