CHANGE IN ACCUMULATED OTHER COMPREHENSIVE LOSS - Schedule of Components of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			$ 2,477,636
Other comprehensive income (loss)	$ 138,945	$ (128,942)	82,680	$ (117,542)
Less: Amounts reclassified from accumulated other comprehensive loss	3,916	4,290	11,294	12,675
Net current-period other comprehensive (loss) income	142,861	(124,652)	93,974	(104,867)
Ending balance	2,678,264		2,678,264
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(642,878)	(656,059)	(593,991)	(675,844)
Net current-period other comprehensive (loss) income	142,861	(124,652)	93,974	(104,867)
Ending balance	(500,017)	(780,711)	(500,017)	(780,711)
Net change in investment securities available-for-sale
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(549,039)	(550,890)	(499,932)	(563,533)
Other comprehensive income (loss)	128,223	(127,523)	79,116	(114,880)
Less: Amounts reclassified from accumulated other comprehensive loss	0	0	0	0
Net current-period other comprehensive (loss) income	128,223	(127,523)	79,116	(114,880)
Ending balance	(420,816)	(678,413)	(420,816)	(678,413)
Net change in investment securities held-to-maturity
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(84,046)	(99,945)	(91,523)	(108,503)
Other comprehensive income (loss)	0	0	0	0
Less: Amounts reclassified from accumulated other comprehensive loss	3,965	4,366	11,442	12,924
Net current-period other comprehensive (loss) income	3,965	4,366	11,442	12,924
Ending balance	(80,081)	(95,579)	(80,081)	(95,579)
Net change in defined benefit plan
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(4,790)	(4,571)	(4,614)	(4,482)
Other comprehensive income (loss)	(4)	(3)	(81)	2
Less: Amounts reclassified from accumulated other comprehensive loss	(49)	(48)	(148)	(142)
Net current-period other comprehensive (loss) income	(53)	(51)	(229)	(140)
Ending balance	(4,843)	(4,622)	(4,843)	(4,622)
Net change in fair value of derivatives used for cash flow hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(5,423)	(1,115)	1,597	108
Other comprehensive income (loss)	10,722	(1,608)	3,702	(2,752)
Less: Amounts reclassified from accumulated other comprehensive loss	0	(28)	0	(107)
Net current-period other comprehensive (loss) income	10,722	(1,636)	3,702	(2,859)
Ending balance	5,299	(2,751)	5,299	(2,751)
Net change in equity method investments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	420	462	481	566
Other comprehensive income (loss)	4	192	(57)	88
Less: Amounts reclassified from accumulated other comprehensive loss	0	0	0	0
Net current-period other comprehensive (loss) income	4	192	(57)	88
Ending balance	$ 424	$ 654	$ 424	$ 654