FINANCIAL DERIVATIVES - Schedule of Net Income/(Expense) Recognized (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Derivative Instruments, Gain (Loss) [Line Items]
Interest Income Investments and Cash Equivalents	$ 846,441	$ 974,329	$ 877,394
Interest Income Loans	765,806	629,187	514,894
Total Interest Expense	(1,221,513)	(1,249,649)	(1,064,741)
Gains (losses) on financial derivatives	(5,120)	2,636	2,882
Designated as hedge
Derivative Instruments, Gain (Loss) [Line Items]
Interest Income Investments and Cash Equivalents	846,441	974,329	877,394
Interest Income Loans	765,806	629,187	514,894
Total Interest Expense	(1,221,513)	(1,249,649)	(1,064,741)
Gains (losses) on financial derivatives	(5,120)	2,636	2,882
Total	385,614	356,503	330,429
Designated as hedge | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on hedged items	(42,098)	(95,850)	(61,506)
Premium/discount amortization recognized on hedged items	(55)	(1,063)	(1,005)
(Losses)/gains on fair value hedging relationships, recognized on hedged items	73,945	(246,695)	(151,073)
Gains/(losses) on fair value hedging relationships	6,778	11,548	(5,394)
Designated as hedge | Cash flow hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Premium/discount amortization recognized on hedged items	(68)	(34)	(55)
Interest settlements reclassified from AOCI into net income on derivatives	14,140	20,657	20,643
Recognized on hedged items	(23,454)	(31,241)	(31,610)
Expense recognized on cash flow hedges	(9,382)	(10,618)	(11,022)
Designated as hedge | Interest Income Investments and Cash Equivalents | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on hedged items	284,605	258,062	216,884
Premium/discount amortization recognized on hedged items	2,551	2,134	1,860
(Losses)/gains on fair value hedging relationships, recognized on hedged items	188,506	(78,424)	107,909
Gains/(losses) on fair value hedging relationships	(435)	3,251	(2,687)
Designated as hedge | Interest Income Investments and Cash Equivalents | Cash flow hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Premium/discount amortization recognized on hedged items	0	0	0
Interest settlements reclassified from AOCI into net income on derivatives	0	0	0
Recognized on hedged items	0	0	0
Expense recognized on cash flow hedges	0	0	0
Designated as hedge | Interest Income Loans | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on hedged items	83,603	69,516	63,133
Premium/discount amortization recognized on hedged items	0	0	0
(Losses)/gains on fair value hedging relationships, recognized on hedged items	41,128	(66,852)	21,686
Gains/(losses) on fair value hedging relationships	2,919	4,361	(1,842)
Designated as hedge | Interest Income Loans | Cash flow hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Premium/discount amortization recognized on hedged items	0	0	0
Interest settlements reclassified from AOCI into net income on derivatives	0	0	0
Recognized on hedged items	0	0	0
Expense recognized on cash flow hedges	0	0	0
Designated as hedge | Total Interest Expense | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on hedged items	(410,306)	(423,428)	(341,523)
Premium/discount amortization recognized on hedged items	(2,606)	(3,197)	(2,865)
(Losses)/gains on fair value hedging relationships, recognized on hedged items	(155,689)	(101,419)	(280,668)
Gains/(losses) on fair value hedging relationships	4,294	3,936	(865)
Designated as hedge | Total Interest Expense | Cash flow hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Premium/discount amortization recognized on hedged items	(68)	(34)	(55)
Interest settlements reclassified from AOCI into net income on derivatives	14,140	20,657	20,643
Recognized on hedged items	(23,454)	(31,241)	(31,610)
Expense recognized on cash flow hedges	(9,382)	(10,618)	(11,022)
Designated as hedge | Losses on financial derivatives | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on hedged items	0	0	0
Premium/discount amortization recognized on hedged items	0	0	0
(Losses)/gains on fair value hedging relationships, recognized on hedged items	0	0	0
Gains/(losses) on fair value hedging relationships	0	0	0
Designated as hedge | Losses on financial derivatives | Cash flow hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Premium/discount amortization recognized on hedged items	0	0	0
Interest settlements reclassified from AOCI into net income on derivatives	0	0	0
Recognized on hedged items	0	0	0
Expense recognized on cash flow hedges	0	0	0
Designated as hedge | Interest Rate Swap | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on derivatives	57,645	(18,895)	(99,800)
Income/(expense) related to interest settlements on fair value hedging relationships	15,492	(115,808)	(162,311)
(Losses)/gains on fair value hedging relationships, recognized on derivatives	(67,167)	258,243	145,679
Designated as hedge | Interest Rate Swap | Interest Income Investments and Cash Equivalents | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on derivatives	113,183	188,146	181,404
Income/(expense) related to interest settlements on fair value hedging relationships	400,339	448,342	400,148
(Losses)/gains on fair value hedging relationships, recognized on derivatives	(188,941)	81,675	(110,596)
Designated as hedge | Interest Rate Swap | Interest Income Loans | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on derivatives	48,551	68,346	64,648
Income/(expense) related to interest settlements on fair value hedging relationships	132,154	137,862	127,781
(Losses)/gains on fair value hedging relationships, recognized on derivatives	(38,209)	71,213	(23,528)
Designated as hedge | Interest Rate Swap | Total Interest Expense | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on derivatives	(104,089)	(275,387)	(345,852)
Income/(expense) related to interest settlements on fair value hedging relationships	(517,001)	(702,012)	(690,240)
(Losses)/gains on fair value hedging relationships, recognized on derivatives	159,983	105,355	279,803
Designated as hedge | Interest Rate Swap | Losses on financial derivatives | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on derivatives	0	0	0
Income/(expense) related to interest settlements on fair value hedging relationships	0	0	0
(Losses)/gains on fair value hedging relationships, recognized on derivatives	0	0	0
No hedge designation
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on financial derivatives	(5,120)	2,636	2,882
No hedge designation | Interest Income Investments and Cash Equivalents
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on financial derivatives	0	0	0
No hedge designation | Interest Income Loans
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on financial derivatives	0	0	0
No hedge designation | Total Interest Expense
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on financial derivatives	0	0	0
No hedge designation | Losses on financial derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on financial derivatives	(5,120)	2,636	2,882
No hedge designation | Interest Rate Swap
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on financial derivatives	(2,784)	2,424	4,395
Interest expense on interest rate swaps	(441)	(1,377)	(4,845)
No hedge designation | Interest Rate Swap | Interest Income Investments and Cash Equivalents
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on financial derivatives	0	0	0
Interest expense on interest rate swaps	0	0	0
No hedge designation | Interest Rate Swap | Interest Income Loans
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on financial derivatives	0	0	0
Interest expense on interest rate swaps	0	0	0
No hedge designation | Interest Rate Swap | Total Interest Expense
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on financial derivatives	0	0	0
Interest expense on interest rate swaps	0	0	0
No hedge designation | Interest Rate Swap | Losses on financial derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on financial derivatives	(2,784)	2,424	4,395
Interest expense on interest rate swaps	(441)	(1,377)	(4,845)
No hedge designation | Treasury futures
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on financial derivatives	(1,895)	1,589	3,332
No hedge designation | Treasury futures | Interest Income Investments and Cash Equivalents
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on financial derivatives	0	0	0
No hedge designation | Treasury futures | Interest Income Loans
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on financial derivatives	0	0	0
No hedge designation | Treasury futures | Total Interest Expense
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on financial derivatives	0	0	0
No hedge designation | Treasury futures | Losses on financial derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on financial derivatives	$ (1,895)	$ 1,589	$ 3,332