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DERIVATIVES AND HEDGING ACTIVITIES - Classification on Consolidated Statements of Financial Condition (Details) | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2021 USD ($) DerivativeInstrument | Jun. 30, 2020 USD ($) | Jun. 30, 2021 USD ($) DerivativeInstrument | Jun. 30, 2020 USD ($) | Dec. 31, 2020 USD ($) DerivativeInstrument
Cash Flow Hedges |  |  |  |  |
Fair value liabilities | $ 0 |  | $ 0 |  |
Not Designated as Hedging Instrument [Member] |  |  |  |  |
Cash Flow Hedges |  |  |  |  |
Loan level derivative income | $ 559,000 | $ 2,494,000 | $ 2,351,000 | $ 3,657,000 |
Interest Rate Swaps Related to FHLBNY Advances [Member] | Designated as Hedging Instrument |  |  |  |  |
Cash Flow Hedges |  |  |  |  |
Count, assets | DerivativeInstrument | 4 |  | 4 |  |
Count, liabilities | DerivativeInstrument |  |  |  |  | 32
Notional amount, assets | $ 150,000,000 |  | $ 150,000,000 |  |
Notional amount, liabilities |  |  |  |  | $ 655,000,000
Fair value assets | $ 2,547,000 |  | $ 2,547,000 |  |
Fair value liabilities |  |  |  |  | $ (18,442,000)
Loan Level Interest Rate Swaps with Borrower | Not Designated as Hedging Instrument [Member] |  |  |  |  |
Cash Flow Hedges |  |  |  |  |
Count, assets | DerivativeInstrument | 137 |  | 137 |  | 65
Count, liabilities | DerivativeInstrument | 49 |  | 49 |  |
Notional amount, assets | $ 937,092,000 |  | $ 937,092,000 |  | $ 570,277,000
Notional amount, liabilities | 314,786,000 |  | 314,786,000 |  |
Fair value assets | 42,753,000 |  | 42,753,000 |  | $ 24,764,000
Fair value liabilities | $ (4,750,000) |  | $ (4,750,000) |  |
Loan Level Interest Rate Floors with Borrower [Member] | Not Designated as Hedging Instrument [Member] |  |  |  |  |
Cash Flow Hedges |  |  |  |  |
Count, assets | DerivativeInstrument | 47 |  | 47 |  |
Count, liabilities | DerivativeInstrument |  |  |  |  | 41
Notional amount, assets | $ 407,249,000 |  | $ 407,249,000 |  |
Notional amount, liabilities |  |  |  |  | $ 364,643,000
Fair value assets | 0 |  | 0 |  |
Fair value liabilities | (4,743,000) |  | (4,743,000) |  | $ (5,832,000)
Loan Level Interest Rate Swaps with Third-part Counterparties [Member] | Designated as Hedging Instrument |  |  |  |  |
Cash Flow Hedges |  |  |  |  |
Posted collateral | $ 0 |  | $ 0 |  |
Loan Level Interest Rate Swaps with Third-part Counterparties [Member] | Not Designated as Hedging Instrument [Member] |  |  |  |  |
Cash Flow Hedges |  |  |  |  |
Count, assets | DerivativeInstrument | 137 |  | 137 |  |
Count, liabilities | DerivativeInstrument | 49 |  | 49 |  | 65
Notional amount, assets | $ 937,092,000 |  | $ 937,092,000 |  |
Notional amount, liabilities | 314,786,000 |  | 314,786,000 |  | $ 570,277,000
Fair value assets | 4,750,000 |  | 4,750,000 |  |
Fair value liabilities | (42,753,000) |  | (42,753,000) |  | $ (24,764,000)
Posted collateral | $ 30,200,000 |  | $ 30,200,000 |  |
Loan Level Interest Rate Floors with Third-part Counterparties [Member] | Not Designated as Hedging Instrument [Member] |  |  |  |  |
Cash Flow Hedges |  |  |  |  |
Count, assets | DerivativeInstrument | 47 |  | 47 |  | 41
Notional amount, assets | $ 407,249,000 |  | $ 407,249,000 |  | $ 364,643,000
Fair value assets | 4,743,000 |  | 4,743,000 |  | $ 5,832,000
Fair value liabilities | $ 0 |  | $ 0 |  |

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