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FAIR VALUE OF FINANCIAL INSTRUMENTS - Assets and Liabilities Measured at Fair Value on a Recurring and Nonrecurring Basis (Details) - USD ($) | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2021 | Jun. 30, 2020 | Jun. 30, 2021 | Jun. 30, 2020 | Dec. 31, 2020
Financial Assets |  |  |  |  |
Derivative assets | $ 45,439,000 |  | $ 45,439,000 |  | $ 18,932,000
Financial Liabilities |  |  |  |  |
Derivative liabilities | 42,892,000 |  | 42,892,000 |  | 37,374,000
Impaired Loans [Abstract] |  |  |  |  |
Individually evaluated CRE loans with an allowance for credit losses, Outstanding balance |  |  |  |  | 12,502,000
Valuation allowance |  |  |  |  | 6,474,000
Provision for credit losses | (4,248,000) | $ 6,060,000 | 11,531,000 | $ 14,072,000 |
Recurring | Cash flow hedges |  |  |  |  |
Financial Assets |  |  |  |  |
Derivative assets | 2,547,000 |  | 2,547,000 |  |
Financial Liabilities |  |  |  |  |
Derivative liabilities |  |  |  |  | 18,442,000
Recurring | Freestanding derivatives |  |  |  |  |
Financial Assets |  |  |  |  |
Derivative assets | 42,892,000 |  | 42,892,000 |  | 30,596,000
Financial Liabilities |  |  |  |  |
Derivative liabilities | 42,892,000 |  | 42,892,000 |  | 30,596,000
Recurring | Level 2 Inputs [Member] | Cash flow hedges |  |  |  |  |
Financial Assets |  |  |  |  |
Derivative assets | 2,547,000 |  | 2,547,000 |  |
Financial Liabilities |  |  |  |  |
Derivative liabilities |  |  |  |  | 18,442,000
Recurring | Level 2 Inputs [Member] | Freestanding derivatives |  |  |  |  |
Financial Assets |  |  |  |  |
Derivative assets | 42,892,000 |  | 42,892,000 |  | 30,596,000
Financial Liabilities |  |  |  |  |
Derivative liabilities | 42,892,000 |  | 42,892,000 |  | 30,596,000
Nonrecurring [Member] |  |  |  |  |
Impaired Loans [Abstract] |  |  |  |  |
Individually evaluated CRE loans with an allowance for credit losses, Outstanding balance | 71,600,000 |  | 71,600,000 |  |
Valuation allowance | 23,700,000 |  | 23,700,000 |  |
Provision for credit losses | 500,000 |  | 400,000 |  |
Carrying amount of impaired loans |  |  |  |  | 0
Nonrecurring [Member] | Level 3 Inputs [Member] |  |  |  |  |
Impaired Loans [Abstract] |  |  |  |  |
Individually evaluated loans | 47,951,000 |  | 47,951,000 |  |
Carrying Amount | Nonrecurring [Member] |  |  |  |  |
Impaired Loans [Abstract] |  |  |  |  |
Individually evaluated loans | 47,951,000 |  | 47,951,000 |  |
Agency Notes | Recurring |  |  |  |  |
Financial Assets |  |  |  |  |
Securities available-for-sale: | 81,035,000 |  | 81,035,000 |  | 47,421,000
Agency Notes | Recurring | Level 2 Inputs [Member] |  |  |  |  |
Financial Assets |  |  |  |  |
Securities available-for-sale: | 81,035,000 |  | 81,035,000 |  | 47,421,000
Treasury Securities | Recurring |  |  |  |  |
Financial Assets |  |  |  |  |
Securities available-for-sale: | 167,998,000 |  | 167,998,000 |  |
Treasury Securities | Recurring | Level 2 Inputs [Member] |  |  |  |  |
Financial Assets |  |  |  |  |
Securities available-for-sale: | 167,998,000 |  | 167,998,000 |  |
Corporate Securities | Recurring |  |  |  |  |
Financial Assets |  |  |  |  |
Securities available-for-sale: | 108,064,000 |  | 108,064,000 |  | 64,461,000
Corporate Securities | Recurring | Level 2 Inputs [Member] |  |  |  |  |
Financial Assets |  |  |  |  |
Securities available-for-sale: | 108,064,000 |  | 108,064,000 |  | 64,461,000
Pass-through MBS issued by GSEs | Recurring |  |  |  |  |
Financial Assets |  |  |  |  |
Securities available-for-sale: |  |  |  |  | 143,483,000
Mortgage-backed securities | 331,749,000 |  | 331,749,000 |  |
Pass-through MBS issued by GSEs | Recurring | Level 2 Inputs [Member] |  |  |  |  |
Financial Assets |  |  |  |  |
Securities available-for-sale: |  |  |  |  | 143,483,000
Mortgage-backed securities | 331,749,000 |  | 331,749,000 |  |
Agency CMOs [Member] | Recurring |  |  |  |  |
Financial Assets |  |  |  |  |
Securities available-for-sale: | 531,490,000 |  | 531,490,000 |  | 283,496,000
Agency CMOs [Member] | Recurring | Level 2 Inputs [Member] |  |  |  |  |
Financial Assets |  |  |  |  |
Securities available-for-sale: | 531,490,000 |  | 531,490,000 |  | 283,496,000
State and municipal obligations | Recurring |  |  |  |  |
Financial Assets |  |  |  |  |
Securities available-for-sale: | 41,452,000 |  | 41,452,000 |  |
State and municipal obligations | Recurring | Level 2 Inputs [Member] |  |  |  |  |
Financial Assets |  |  |  |  |
Securities available-for-sale: | $ 41,452,000 |  | $ 41,452,000 |  |
Domestic Equity Mutual Funds | Recurring |  |  |  |  |
Financial Assets |  |  |  |  |
Marketable equity securities (Registered Mutual Funds) |  |  |  |  | 1,769,000
Domestic Equity Mutual Funds | Recurring | Level 1 Inputs [Member] |  |  |  |  |
Financial Assets |  |  |  |  |
Marketable equity securities (Registered Mutual Funds) |  |  |  |  | 1,769,000
International Equity Mutual Funds | Recurring |  |  |  |  |
Financial Assets |  |  |  |  |
Marketable equity securities (Registered Mutual Funds) |  |  |  |  | 468,000
International Equity Mutual Funds | Recurring | Level 1 Inputs [Member] |  |  |  |  |
Financial Assets |  |  |  |  |
Marketable equity securities (Registered Mutual Funds) |  |  |  |  | 468,000
Fixed Income Mutual Funds | Recurring |  |  |  |  |
Financial Assets |  |  |  |  |
Marketable equity securities (Registered Mutual Funds) |  |  |  |  | 3,733,000
Fixed Income Mutual Funds | Recurring | Level 1 Inputs [Member] |  |  |  |  |
Financial Assets |  |  |  |  |
Marketable equity securities (Registered Mutual Funds) |  |  |  |  | $ 3,733,000

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