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DERIVATIVES AND HEDGING ACTIVITIES - Classification on Consolidated Statements of Financial Condition (Details) | 12 Months Ended
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Dec. 31, 2021 USD ($) DerivativeInstrument | Dec. 31, 2020 USD ($) DerivativeInstrument | Dec. 31, 2019 USD ($)
Not Designated as Hedging Instrument [Member] |  |  |
Cash Flow Hedges |  |  |
Loan level derivative income | $ 2,909,000 | $ 8,872,000 | $ 910,000
Interest Rate Swaps Related to FHLBNY Advances [Member] | Designated as Hedging Instrument |  |  |
Cash Flow Hedges |  |  |
Count, assets | DerivativeInstrument | 4 |  |
Count, liabilities | DerivativeInstrument |  | 32 |
Notional amount, assets | $ 150,000,000 |  |
Notional amount, liabilities |  | $ 655,000,000 |
Fair value assets | $ 4,358,000 |  |
Fair value liabilities |  | $ (18,442,000) |
Loan Level Interest Rate Swaps with Borrower (Assets) | Not Designated as Hedging Instrument [Member] |  |  |
Cash Flow Hedges |  |  |
Count, assets | DerivativeInstrument | 111 | 65 |
Notional amount, assets | $ 604,529,000 | $ 570,277,000 |
Fair value assets | $ 28,291,000 | $ 24,764,000 |
Loan Level Interest Rate Swaps with Borrower (Liabilities) | Not Designated as Hedging Instrument [Member] |  |  |
Cash Flow Hedges |  |  |
Count, liabilities | DerivativeInstrument | 74 |  |
Notional amount, liabilities | $ 620,459,000 |  |
Fair value liabilities | (11,865,000) |  |
Posted collateral | $ 0 |  |
Loan Level Interest Rate Floors with Borrower [Member] | Not Designated as Hedging Instrument [Member] |  |  |
Cash Flow Hedges |  |  |
Count, liabilities | DerivativeInstrument | 45 | 41 |
Notional amount, liabilities | $ 392,764,000 | $ 364,643,000 |
Fair value liabilities | (5,644,000) | (5,832,000) |
Loan Level Interest Rate Swaps with Third-part Counterparties [Member] | Designated as Hedging Instrument |  |  |
Cash Flow Hedges |  |  |
Posted collateral | $ 0 | $ 5,400,000 |
Loan Level Interest Rate Swaps with Third-part Counterparties [Member] | Not Designated as Hedging Instrument [Member] |  |  |
Cash Flow Hedges |  |  |
Count, liabilities | DerivativeInstrument | 111 | 65 |
Notional amount, liabilities | $ 604,529,000 | $ 570,277,000 |
Fair value liabilities | (28,291,000) | $ (24,764,000) |
Posted collateral | $ 14,000,000.0 |  |
Loan level interest rate swaps with third party counterparties (Assets) | Not Designated as Hedging Instrument [Member] |  |  |
Cash Flow Hedges |  |  |
Count, assets | DerivativeInstrument | 74 |  |
Notional amount, assets | $ 620,459,000 |  |
Fair value assets | $ 11,865,000 |  |
Loan Level Interest Rate Floors with Third-part Counterparties [Member] | Not Designated as Hedging Instrument [Member] |  |  |
Cash Flow Hedges |  |  |
Count, assets | DerivativeInstrument | 45 | 41 |
Notional amount, assets | $ 392,764,000 | $ 364,643,000 |
Fair value assets | $ 5,644,000 | $ 5,832,000 |

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