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, 2024	Dec. 31, 2023
Notional Disclosures [Abstract]
Notional Amount	$ 25,569,003	$ 25,779,468
Asset
Fair value, asset	53,686	37,478
Netting adjustments	(2,321)	(1,236)
(Liability)
Fair value, liability	(118,421)	(117,131)
Netting adjustments	2,321	1,236
Designated as hedge | Fair value hedges: | Receive fixed non-callable
Notional Disclosures [Abstract]
Notional Amount	8,694,685	9,174,253
Asset
Fair value, asset	728	7,767
(Liability)
Fair value, liability	$ (21,529)	$ (1,081)
Weighted- Average Pay Rate	5.54%	2.50%
Weighted- Average Receive Rate	3.21%	5.47%
Weighted- Average Remaining Term (in years)	1 year 8 months 1 day	9 years 6 months 25 days
Designated as hedge | Fair value hedges: | Pay fixed non-callable
Notional Disclosures [Abstract]
Notional Amount	$ 9,259,875	$ 9,776,685
Asset
Fair value, asset	31,027	2,350
(Liability)
Fair value, liability	$ (237)	$ (20,390)
Weighted- Average Pay Rate	2.58%	5.57%
Weighted- Average Receive Rate	5.41%	2.94%
Weighted- Average Remaining Term (in years)	9 years 3 months 18 days	1 year 9 months 10 days
Designated as hedge | Fair value hedges: | Receive fixed callable
Notional Disclosures [Abstract]
Notional Amount	$ 4,229,327	$ 3,879,827
Asset
Fair value, asset	1,257	7,374
(Liability)
Fair value, liability	$ (98,425)	$ (95,984)
Weighted- Average Pay Rate	5.35%	5.40%
Weighted- Average Receive Rate	3.61%	3.40%
Weighted- Average Remaining Term (in years)	2 years 6 months 7 days	2 years 5 months 23 days
Designated as hedge | Cash flow hedges: | Pay fixed non-callable
Notional Disclosures [Abstract]
Notional Amount	$ 540,000	$ 558,000
Asset
Fair value, asset	21,562	20,234
(Liability)
Fair value, liability	$ (8)	$ (43)
Weighted- Average Pay Rate	1.92%	1.94%
Weighted- Average Receive Rate	5.79%	5.82%
Weighted- Average Remaining Term (in years)	3 years 11 months 4 days	4 years 3 months 18 days
No hedge designation | Receive fixed non-callable
Notional Disclosures [Abstract]
Notional Amount	$ 1,974,899	$ 1,358,396
Asset
Fair value, asset	117	263
(Liability)
Fair value, liability	$ (1)	$ (3)
Weighted- Average Pay Rate	5.36%	5.44%
Weighted- Average Receive Rate	5.12%	4.87%
Weighted- Average Remaining Term (in years)	3 months 14 days	7 months 20 days
No hedge designation | Pay fixed non-callable
Notional Disclosures [Abstract]
Notional Amount	$ 157,933	$ 160,623
Asset
Fair value, asset	1,115	676
(Liability)
Fair value, liability	$ (4)	$ (29)
Weighted- Average Pay Rate	2.92%	2.92%
Weighted- Average Receive Rate	5.59%	5.64%
Weighted- Average Remaining Term (in years)	3 years 10 months 28 days	4 years 4 months 2 days
No hedge designation | Basis swaps
Notional Disclosures [Abstract]
Notional Amount	$ 685,384	$ 850,384
Asset
Fair value, asset	38	39
(Liability)
Fair value, liability	$ (534)	$ (746)
Weighted- Average Pay Rate	5.52%	5.52%
Weighted- Average Receive Rate	5.49%	5.48%
Weighted- Average Remaining Term (in years)	4 years 1 month 24 days	3 years 9 months 29 days
No hedge designation | Treasury futures
Notional Disclosures [Abstract]
Notional Amount	$ 26,900	$ 21,300
Asset
Fair value, asset	163	11
Netting adjustments	(2,321)	(1,236)
(Liability)
Fair value, liability	(4)	(91)
Netting adjustments	$ 2,321	$ 1,236
Weighted- Average Forward Price (in dollars per share)	$ 110.58	$ 112.51