FAIR VALUE OF FINANCIAL INSTRUMENTS - Assets and Liabilities Measured at Fair Value on a Recurring and Nonrecurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Financial Assets
Derivative assets	$ 135,162	$ 122,132
Financial Liabilities
Derivative liabilities	122,112	121,265
Recurring | Fair value hedges
Financial Liabilities
Derivative liabilities	1,353	6,594
Recurring | Cash flow hedges
Financial Assets
Derivative assets	13,107	7,461
Financial Liabilities
Derivative liabilities	1,067
Recurring | Freestanding derivatives, net
Financial Assets
Derivative assets	122,055	114,671
Financial Liabilities
Derivative liabilities	122,055	114,671
Recurring | Level 2 Inputs | Fair value hedges
Financial Liabilities
Derivative liabilities	1,353	6,594
Recurring | Level 2 Inputs | Cash flow hedges
Financial Assets
Derivative assets	13,107	7,461
Financial Liabilities
Derivative liabilities	1,067
Recurring | Level 2 Inputs | Freestanding derivatives, net
Financial Assets
Derivative assets	122,055	114,671
Financial Liabilities
Derivative liabilities	122,055	114,671
Nonrecurring | Level 3 Inputs
Certain individually evaluated loans
Individually evaluated loans	854	6,336
Carrying Amount
Certain individually evaluated loans
Individually evaluated loans	10,687,661	10,695,349
Carrying Amount | Nonrecurring
Certain individually evaluated loans
Individually evaluated loans	854	6,336
US Government Agencies Debt Securities [Member] | Recurring
Financial Assets
Securities available-for-sale:	9,409	9,371
US Government Agencies Debt Securities [Member] | Recurring | Level 2 Inputs
Financial Assets
Securities available-for-sale:	9,409	9,371
US Treasury Securities [Member] | Recurring
Financial Assets
Securities available-for-sale:	228,171	234,190
US Treasury Securities [Member] | Recurring | Level 2 Inputs
Financial Assets
Securities available-for-sale:	228,171	234,190
Corporate securities | Recurring
Financial Assets
Securities available-for-sale:	150,245	151,170
Corporate securities | Recurring | Level 2 Inputs
Financial Assets
Securities available-for-sale:	150,245	151,170
Pass-through mortgage-backed securities ("MBS") issued by government sponsored entities ("GSEs") | Recurring
Financial Assets
Mortgage-backed securities	195,876	205,285
Pass-through mortgage-backed securities ("MBS") issued by government sponsored entities ("GSEs") | Recurring | Level 2 Inputs
Financial Assets
Mortgage-backed securities	195,876	205,285
Agency collateralized mortgage obligations ("CMOs") | Recurring
Financial Assets
Securities available-for-sale:	249,840	259,415
Agency collateralized mortgage obligations ("CMOs") | Recurring | Level 2 Inputs
Financial Assets
Securities available-for-sale:	249,840	259,415
State and municipal obligations | Recurring
Financial Assets
Securities available-for-sale:	25,675	26,809
State and municipal obligations | Recurring | Level 2 Inputs
Financial Assets
Securities available-for-sale:	$ 25,675	$ 26,809