FAIR VALUE MEASUREMENTS - Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Debt securities:
Available for sale debt securities, at fair value	$ 623,499	$ 625,074
Held to maturity	8,393	10,349
Equity securities	12,070	11,782
Carrying Amount
Financial assets:
Cash, cash equivalents and restricted cash	214,066	91,325
Debt securities:
Available for sale debt securities, at fair value	623,499	625,074
Held to maturity	7,990	10,170
Equity securities	12,070	11,782
Loans receivable, net	6,102,438	6,194,976
Accrued interest receivable	19,894	20,814
FHLB stock	29,612	30,342
Interest rate swaps		1,156
Financial liabilities:
Deposits	5,276,680	5,234,717
FHLB advances	961,747	978,702
Junior subordinated deferrable interest debentures	61,857	61,857
Senior debt	94,509	94,416
Accrued interest payable	1,254	2,901
Interest rate swaps	10,834	746
Fair Value
Financial assets:
Cash, cash equivalents and restricted cash	214,066	91,325
Debt securities:
Available for sale debt securities, at fair value	623,499	625,074
Held to maturity	8,393	10,349
Equity securities	12,070	11,782
Loans receivable, net	6,158,846	6,346,496
Accrued interest receivable	19,894	20,814
Interest rate swaps		1,156
Financial liabilities:
Deposits	5,310,264	5,253,511
FHLB advances	1,003,764	996,860
Junior subordinated deferrable interest debentures	55,751	59,272
Senior debt	102,783	99,806
Accrued interest payable	1,254	2,901
Interest rate swaps	10,834	746
Fair Value \| Level 1
Financial assets:
Cash, cash equivalents and restricted cash	214,066	91,325
Debt securities:
Available for sale debt securities, at fair value	0	0
Held to maturity	0	0
Equity securities	0	0
Loans receivable, net	0	0
Accrued interest receivable	3	26
Interest rate swaps		0
Financial liabilities:
Deposits	1,938,466	1,558,029
FHLB advances	0	0
Junior subordinated deferrable interest debentures	0	0
Senior debt	0	0
Accrued interest payable	0	0
Interest rate swaps	0	0
Fair Value \| Level 2
Financial assets:
Cash, cash equivalents and restricted cash	0	0
Debt securities:
Available for sale debt securities, at fair value	623,499	625,074
Held to maturity	8,393	10,349
Equity securities	12,070	11,782
Loans receivable, net	0	0
Accrued interest receivable	1,083	1,685
Interest rate swaps		1,156
Financial liabilities:
Deposits	3,371,798	3,695,482
FHLB advances	1,003,764	996,860
Junior subordinated deferrable interest debentures	55,751	59,272
Senior debt	102,783	99,806
Accrued interest payable	1,254	2,901
Interest rate swaps	10,834	746
Fair Value \| Level 3
Financial assets:
Cash, cash equivalents and restricted cash	0	0
Debt securities:
Available for sale debt securities, at fair value	0	0
Held to maturity	0	0
Equity securities	0	0
Loans receivable, net	6,158,846	6,346,496
Accrued interest receivable	18,808	19,103
Interest rate swaps		0
Financial liabilities:
Deposits	0	0
FHLB advances	0	0
Junior subordinated deferrable interest debentures	0	0
Senior debt	0	0
Accrued interest payable	0	0
Interest rate swaps	$ 0	$ 0

Accrued Interest Payable, Fair Value Disclosure

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Accrued Interest Receivable, Fair Value Disclosure

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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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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

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Fair value portion of deposit liabilities held by the entity, including, but not limited to, foreign and domestic, interest and noninterest bearing, demand deposits, saving deposits, negotiable orders of withdrawal (NOW) and time deposits.

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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

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Fair value of subordinated debt obligations including, but not limited to, subordinated loan, subordinated bond, subordinated debenture or junior debt.

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Fair value portion of borrowing from Federal Home Loan Bank (FHLBank).

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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

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Fair value portion of investments in Federal Home Loan Bank (FHLBank) stock.

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Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

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