FINANCIAL DERIVATIVES - Schedule of Derivative Instruments in Statement of Financial Position (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2026	Dec. 31, 2025
Notional Disclosures [Abstract]
Notional Amount	$ 28,778,467	$ 25,577,094
Asset
Fair value, asset	42,411	44,875
Netting adjustments	(2,460)	(1,631)
(Liability)
Fair value, liability	(69,282)	(21,618)
Netting adjustments	2,460	1,631
Receive fixed non-callable | No hedge designation
Notional Disclosures [Abstract]
Notional Amount	1,555,069	1,963,363
Asset
Fair value, asset	33	66
(Liability)
Fair value, liability	$ (120)	$ (9)
Weighted- Average Pay Rate	3.73%	3.89%
Weighted- Average Receive Rate	3.71%	3.93%
Weighted- Average Remaining Term (in years)	4 months 17 days	3 months 10 days
Receive fixed non-callable | Fair value hedges: | Designated as hedge
Notional Disclosures [Abstract]
Notional Amount	$ 6,712,235	$ 10,681,418
Asset
Fair value, asset	1	16,685
(Liability)
Fair value, liability	$ (2,893)	$ (168)
Weighted- Average Pay Rate	3.88%	2.79%
Weighted- Average Receive Rate	3.66%	3.93%
Weighted- Average Remaining Term (in years)	11 months 26 days	8 years 7 months 28 days
Pay fixed non-callable | No hedge designation
Notional Disclosures [Abstract]
Notional Amount	$ 155,697	$ 159,684
Asset
Fair value, asset	667	613
(Liability)
Fair value, liability	$ (20)	$ (1)
Weighted- Average Pay Rate	2.86%	2.88%
Weighted- Average Receive Rate	3.94%	4.13%
Weighted- Average Remaining Term (in years)	3 years 3 months 7 days	3 years 7 months 9 days
Pay fixed non-callable | Fair value hedges: | Designated as hedge
Notional Disclosures [Abstract]
Notional Amount	$ 12,035,992	$ 6,388,935
Asset
Fair value, asset	33,747	330
(Liability)
Fair value, liability	$ (39)	$ (2,954)
Weighted- Average Pay Rate	2.96%	4.08%
Weighted- Average Receive Rate	3.72%	3.56%
Weighted- Average Remaining Term (in years)	8 years 7 months 6 days	1 year 1 month 13 days
Pay fixed non-callable | Cash flow hedges: | Designated as hedge
Notional Disclosures [Abstract]
Notional Amount	$ 440,000	$ 452,000
Asset
Fair value, asset	8,952	9,335
(Liability)
Fair value, liability	$ 0	$ (1)
Weighted- Average Pay Rate	1.90%	1.92%
Weighted- Average Receive Rate	4.11%	4.22%
Weighted- Average Remaining Term (in years)	2 years 7 months 2 days	3 years
Receive fixed callable | Fair value hedges: | Designated as hedge
Notional Disclosures [Abstract]
Notional Amount	$ 7,501,163	$ 5,446,883
Asset
Fair value, asset	1,425	19,322
(Liability)
Fair value, liability	$ (68,549)	$ (19,911)
Weighted- Average Pay Rate	3.78%	3.96%
Weighted- Average Receive Rate	3.84%	3.73%
Weighted- Average Remaining Term (in years)	3 years 5 months 19 days	3 years 1 month 20 days
Basis swaps | No hedge designation
Notional Disclosures [Abstract]
Notional Amount	$ 347,811	$ 382,811
Asset
Fair value, asset	3	1
(Liability)
Fair value, liability	$ (99)	$ (190)
Weighted- Average Pay Rate	3.91%	4.13%
Weighted- Average Receive Rate	3.82%	3.89%
Weighted- Average Remaining Term (in years)	5 years	5 years 10 days
Treasury futures | No hedge designation
Notional Disclosures [Abstract]
Notional Amount	$ 30,500	$ 102,000
Asset
Fair value, asset	43	154
Netting adjustments	(2,460)	(1,631)
(Liability)
Fair value, liability	(22)	(15)
Netting adjustments	$ 2,460	$ 1,631
Weighted- Average Forward Price (in dollars per share)	$ 109.96	$ 112.57