CHANGE IN ACCUMULATED OTHER COMPREHENSIVE LOSS - Components of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2023	Mar. 31, 2022
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 2,205,113
Other comprehensive (loss) income	53,350	$ (275,861)
Less: Amounts reclassified from accumulated other comprehensive loss	4,079	(151)
Net current-period other comprehensive (loss) income	57,429	(276,012)
Ending balance	2,306,362
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(675,844)	(37,768)
Ending balance	(618,415)	(313,780)
Net change in investment securities available-for-sale
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(563,533)	(33,873)
Other comprehensive (loss) income	53,010	(275,918)
Less: Amounts reclassified from accumulated other comprehensive loss	0	0
Net current-period other comprehensive (loss) income	53,010	(275,918)
Ending balance	(510,523)	(309,791)
Net change in investment securities held-to-maturity
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(108,503)	175
Other comprehensive (loss) income	(1)	56
Less: Amounts reclassified from accumulated other comprehensive loss	4,166	(84)
Net current-period other comprehensive (loss) income	4,165	(28)
Ending balance	(104,338)	147
Net change in defined benefit plan
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(4,482)	(4,691)
Other comprehensive (loss) income	12	0
Less: Amounts reclassified from accumulated other comprehensive loss	(47)	(27)
Net current-period other comprehensive (loss) income	(35)	(27)
Ending balance	(4,517)	(4,718)
Net change in fair value of derivatives used for cash flow hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	108	268
Other comprehensive (loss) income	332	1
Less: Amounts reclassified from accumulated other comprehensive loss	(40)	(40)
Net current-period other comprehensive (loss) income	292	(39)
Ending balance	400	229
Net change in equity method investments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	566	353
Other comprehensive (loss) income	(3)	0
Less: Amounts reclassified from accumulated other comprehensive loss	0	0
Net current-period other comprehensive (loss) income	(3)	0
Ending balance	$ 563	$ 353

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount after tax, before reclassification adjustments, of other comprehensive income (loss), attributable to parent.

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Amount after tax of other comprehensive income (loss) attributable to parent entity.

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Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

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