FEDERAL HOME LOAN BANK ADVANCES AND OTHER BORROWINGS - Additional Information (Details) - USD ($)	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Advances from Federal Home Loan Banks	$ 105,000,000	$ 108,000,000
FHLB interest rate	3.20%	3.17%
Advances with fixed maturity dates	$ 105,000,000	$ 108,000,000
Weighted average interest rate on fixed maturity advances	3.20%	3.17%
Short-term or overnight borrowings with FHLB	$ 128,100,000
Rate of overnight borrowings with FHLB	1.81%
FHLB advance	$ 15,000,000
FHLB advance rate	1.79%
Cash flow hedge, term	4 years
Unused commitments from FHLB	$ 1,300,000,000
Unused short-term or overnight borrowings from correspondent banks	22,000,000
Unused short-term or overnight borrowings from FRB	1,500,000,000
Federal Reserve Bank of New York [Member]
Debt Instrument [Line Items]
Short-term or overnight borrowings with FHLB	113,100,000	$ 0
Residential Mortgage [Member] \| Fixed Rate Advances [Member]
Debt Instrument [Line Items]
Mortgages pledged as collateral for advances	347,500,000	496,100,000
Multifamily Mortgage [Member] \| Fixed Rate Advances [Member]
Debt Instrument [Line Items]
Mortgages pledged as collateral for advances	773,100,000	$ 1,000,000,000
Securities [Member] \| Fixed Rate Advances [Member]
Debt Instrument [Line Items]
Mortgages pledged as collateral for advances	$ 154,300,000

Federal Home Loan Bank Advances Activity cash flow hedge, term.

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This element refers to percentage of weighted average interest rate on fixed maturity advances.

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Amount of unused borrowing capacity under the short-term or overnight borrowings financing arrangement with correspondent banks.

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Amount of unused borrowing capacity under the short-term or overnight borrowings financing arrangement with Federal Reserve Bank.

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Amount of borrowings as of the balance sheet date from the Federal Home Loan Bank, which are primarily used to cover shortages in the required reserve balance and liquidity shortages.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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The calculated weighted average interest rate for Federal Home Loan Bank advances outstanding as of the Balance Sheet date.

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The calculated weighted average interest rate for Federal Home Loan Bank advances for the period ended as of the Balance Sheet date.

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The maximum balance outstanding at any month end during the period as of the Balance Sheet date.

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Discloses the single interest rate [if] applicable to the advances from the Federal Home Loan Bank, by branch, as of the Balance Sheet date.

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Amount of advances or credit lines available from the Federal Home Loan Bank (FHLB).

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Amount of the collateral pledged in support of federal home loan bank advances outstanding.

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Amount of Federal Home Loan Bank (FHLB) advances which have fixed interest.

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Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

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