CHANGE IN ACCUMULATED OTHER COMPREHENSIVE LOSS - Schedule of Components of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			$ 2,477,636
Other comprehensive (loss) income	$ (9,729)	$ (41,950)	(56,265)	$ 11,401
Less: Amounts reclassified from accumulated other comprehensive loss	3,758	4,306	7,378	8,384
Net current-period other comprehensive income (loss)	(5,971)	(37,644)	(48,887)	19,785
Ending balance	2,489,580		2,489,580
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(636,907)	(618,415)	(593,991)	(675,844)
Ending balance	(642,878)	(656,059)	(642,878)	(656,059)
Net change in investment securities available-for-sale
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(539,939)	(510,523)	(499,932)	(563,533)
Other comprehensive (loss) income	(9,100)	(40,367)	(49,107)	12,643
Less: Amounts reclassified from accumulated other comprehensive loss	0	0	0	0
Net current-period other comprehensive income (loss)	(9,100)	(40,367)	(49,107)	12,643
Ending balance	(549,039)	(550,890)	(549,039)	(550,890)
Net change in investment securities held-to-maturity
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(87,854)	(104,338)	(91,523)	(108,503)
Other comprehensive (loss) income	0	0	0	0
Less: Amounts reclassified from accumulated other comprehensive loss	3,808	4,393	7,477	8,558
Net current-period other comprehensive income (loss)	3,808	4,393	7,477	8,558
Ending balance	(84,046)	(99,945)	(84,046)	(99,945)
Net change in defined benefit plan
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(4,738)	(4,517)	(4,614)	(4,482)
Other comprehensive (loss) income	(2)	(7)	(77)	5
Less: Amounts reclassified from accumulated other comprehensive loss	(50)	(47)	(99)	(94)
Net current-period other comprehensive income (loss)	(52)	(54)	(176)	(89)
Ending balance	(4,790)	(4,571)	(4,790)	(4,571)
Net change in fair value of derivatives used for cash flow hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(4,836)	400	1,597	108
Other comprehensive (loss) income	(587)	(1,475)	(7,020)	(1,143)
Less: Amounts reclassified from accumulated other comprehensive loss	0	(40)	0	(80)
Net current-period other comprehensive income (loss)	(587)	(1,515)	(7,020)	(1,223)
Ending balance	(5,423)	(1,115)	(5,423)	(1,115)
Net change in equity method investments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	460	563	481	566
Other comprehensive (loss) income	(40)	(101)	(61)	(104)
Less: Amounts reclassified from accumulated other comprehensive loss	0	0	0	0
Net current-period other comprehensive income (loss)	(40)	(101)	(61)	(104)
Ending balance	$ 420	$ 462	$ 420	$ 462