FAIR VALUE OF FINANCIAL INSTRUMENTS, Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Financial Assets
Derivative assets	$ 45,760	$ 18,932
Financial Liabilities
Derivative liabilities	41,816	37,374
Recurring [Member] \| Cash flow hedges
Financial Assets
Derivative assets	3,944
Financial Liabilities
Derivative liabilities		18,442
Recurring [Member] \| Freestanding derivatives
Financial Assets
Derivative assets	41,816	30,596
Financial Liabilities
Derivative liabilities	41,816	30,596
Recurring [Member] \| Level 2 Inputs [Member] \| Cash flow hedges
Financial Assets
Derivative assets	3,944
Financial Liabilities
Derivative liabilities		18,442
Recurring [Member] \| Level 2 Inputs [Member] \| Freestanding derivatives
Financial Assets
Derivative assets	41,816	30,596
Financial Liabilities
Derivative liabilities	41,816	30,596
Nonrecurring [Member]
Impaired Loans [Abstract]
Fair value	0	0
Agency Notes \| Recurring [Member]
Financial Assets
Securities available-for-sale:	69,570	47,421
Agency Notes \| Recurring [Member] \| Level 2 Inputs [Member]
Financial Assets
Securities available-for-sale:	69,570	47,421
Treasury Securities \| Recurring [Member]
Financial Assets
Securities available-for-sale:	92,272
Treasury Securities \| Recurring [Member] \| Level 2 Inputs [Member]
Financial Assets
Securities available-for-sale:	92,272
Corporate Securities \| Recurring [Member]
Financial Assets
Securities available-for-sale:	98,733	64,461
Corporate Securities \| Recurring [Member] \| Level 2 Inputs [Member]
Financial Assets
Securities available-for-sale:	98,733	64,461
Pass-through MBS issued by GSEs \| Recurring [Member]
Financial Assets
Securities available-for-sale:		143,483
Mortgage-backed securities	323,707
Pass-through MBS issued by GSEs \| Recurring [Member] \| Level 2 Inputs [Member]
Financial Assets
Securities available-for-sale:		143,483
Mortgage-backed securities	323,707
Agency Collateralized Mortgage Obligations ("CMOs") \| Recurring [Member]
Financial Assets
Securities available-for-sale:	522,822	283,496
Agency Collateralized Mortgage Obligations ("CMOs") \| Recurring [Member] \| Level 2 Inputs [Member]
Financial Assets
Securities available-for-sale:	522,822	283,496
State and municipal obligations \| Recurring [Member]
Financial Assets
Securities available-for-sale:	45,389
State and municipal obligations \| Recurring [Member] \| Level 2 Inputs [Member]
Financial Assets
Securities available-for-sale:	$ 45,389
Domestic Equity Mutual Funds [Member] \| Recurring [Member]
Financial Assets
Marketable equity securities (Registered Mutual Funds)		1,769
Domestic Equity Mutual Funds [Member] \| Recurring [Member] \| Level 1 Inputs [Member]
Financial Assets
Marketable equity securities (Registered Mutual Funds)		1,769
International Equity Mutual funds [Member] \| Recurring [Member]
Financial Assets
Marketable equity securities (Registered Mutual Funds)		468
International Equity Mutual funds [Member] \| Recurring [Member] \| Level 1 Inputs [Member]
Financial Assets
Marketable equity securities (Registered Mutual Funds)		468
Fixed Income Mutual funds [Member] \| Recurring [Member]
Financial Assets
Marketable equity securities (Registered Mutual Funds)		3,733
Fixed Income Mutual funds [Member] \| Recurring [Member] \| Level 1 Inputs [Member]
Financial Assets
Marketable equity securities (Registered Mutual Funds)		$ 3,733

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