ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - AOCI Components Pre Post & Tax Effect (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized gains (losses), net	$ 207	$ 991	$ 836	$ 259
Reclassification from AOCI, net	165	218	492	573
Total other comprehensive income (loss), before tax	504	1,630	1,800	1,123
Total other comprehensive income (loss), tax	(132)	(421)	(472)	(291)
Total other comprehensive income (loss), net	372	1,209	1,328	832
Net unrealized gains (losses) on cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized gains (losses), before tax	(21)	613	376	(114)
Net unrealized gains (losses), tax	5	(163)	(101)	30
Net unrealized gains (losses), net	(16)	450	275	(84)
Reclassification from AOCI	197	276	597	711
Reclassification from AOCI, tax	(53)	(73)	(160)	(189)
Reclassification from AOCI, net	144	203	437	522
Total other comprehensive income (loss), before tax	176	889	973	597
Total other comprehensive income (loss), tax	(48)	(236)	(261)	(159)
Total other comprehensive income (loss), net	128	653	712	438
Net unrealized gains (losses) on investment securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized gains (losses), before tax	300	720	753	453
Net unrealized gains (losses), tax	(77)	(179)	(192)	(114)
Net unrealized gains (losses), net	223	541	561	339
Reclassification from AOCI	24	18	64	56
Reclassification from AOCI, tax	(6)	(5)	(16)	(14)
Reclassification from AOCI, net	18	13	48	42
Total other comprehensive income (loss), before tax	324	738	817	509
Total other comprehensive income (loss), tax	(83)	(184)	(208)	(128)
Total other comprehensive income (loss), net	241	554	609	381
Defined benefit plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized gains (losses), net	0	0	0	4
Reclassification from AOCI, net	3	2	7	9
Total other comprehensive income (loss), before tax	4	3	10	17
Total other comprehensive income (loss), tax	(1)	(1)	(3)	(4)
Total other comprehensive income (loss), net	3	2	7	13
Net actuarial gain (loss) arising during the period
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized gains (losses), before tax	0	0	0	5
Net unrealized gains (losses), tax	0	0	0	(1)
Net unrealized gains (losses), net	0	0	0	4
Amortization of actuarial (gain) loss to earnings
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from AOCI	4	3	10	12
Reclassification from AOCI, tax	(1)	(1)	(3)	(3)
Reclassification from AOCI, net	$ 3	$ 2	$ 7	$ 9

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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