DERIVATIVE FINANCIAL INSTRUMENTS - Schedule of Fair Value of Derivative Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2026	Dec. 31, 2025
Designated as Hedging Instrument
Derivative [Line Items]
Assets	$ 608	$ 16,463
Liabilities	75,263	1,667
Designated as Hedging Instrument \| Cash flow hedges: \| Interest rate swaps, collars, and floors on loan pools
Derivative [Line Items]
Notional	3,500,000	2,300,000
Assets	608	11,627
Liabilities	72,098	1,667
Designated as Hedging Instrument \| Cash flow hedges: \| Interest rate swaps on borrowings
Derivative [Line Items]
Notional	50,000	50,000
Assets	0	0
Liabilities	0	0
Designated as Hedging Instrument \| Fair value hedges: \| Interest rate swaps on borrowings
Derivative [Line Items]
Notional	800,000	1,100,000
Assets	0	4,836
Liabilities	3,165	0
Designated as Hedging Instrument \| Fair value hedges: \| Interest rate swaps on investment securities
Derivative [Line Items]
Notional	874,407	927,407
Assets	0	0
Liabilities	0	0
Not Designated as Hedging Instrument
Derivative [Line Items]
Assets	318,505	154,365
Liabilities	444,763	257,301
Not Designated as Hedging Instrument \| Interest rate lock commitments
Derivative [Line Items]
Notional	86,924	81,698
Assets	0	583
Liabilities	955	0
Not Designated as Hedging Instrument \| Forward mortgage loan contracts
Derivative [Line Items]
Notional	103,736	120,584
Assets	2,344	0
Liabilities	0	402
Not Designated as Hedging Instrument \| Customer interest rate contracts
Derivative [Line Items]
Notional	11,106,547	9,939,577
Assets	978	76,026
Liabilities	442,395	180,367
Not Designated as Hedging Instrument \| Counterparty interest rate contracts
Derivative [Line Items]
Notional	11,106,547	9,939,577
Assets	314,628	77,597
Liabilities	992	76,442
Not Designated as Hedging Instrument \| Customer foreign currency contracts
Derivative [Line Items]
Notional	31,377	12,086
Assets	361	106
Liabilities	18	27
Not Designated as Hedging Instrument \| Counterparty foreign currency contracts
Derivative [Line Items]
Notional	36,521	11,656
Assets	194	53
Liabilities	$ 403	$ 63