ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - AOCI Components Pre Post & Tax Effect (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized gains (losses), net	$ (251)	$ 139	$ (475)	$ 629
Reclassification from AOCI, net	78	163	184	327
Total other comprehensive income (loss), before tax	(234)	412	(393)	1,296
Total other comprehensive income (loss), tax	61	(110)	102	(340)
Total other comprehensive income (loss), net	(173)	302	(291)	956
Net unrealized gains (losses) on cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized gains (losses), before tax	(246)	113	(415)	397
Net unrealized gains (losses), tax	66	(30)	111	(106)
Net unrealized gains (losses), net	(180)	83	(304)	291
Reclassification from AOCI	73	198	186	400
Reclassification from AOCI, tax	(20)	(53)	(50)	(107)
Reclassification from AOCI, net	53	145	136	293
Total other comprehensive income (loss), before tax	(173)	311	(229)	797
Total other comprehensive income (loss), tax	46	(83)	61	(213)
Total other comprehensive income (loss), net	(127)	228	(168)	584
Net unrealized gains (losses) on investment securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized gains (losses), before tax	(94)	76	(227)	453
Net unrealized gains (losses), tax	23	(20)	56	(115)
Net unrealized gains (losses), net	(71)	56	(171)	338
Reclassification from AOCI	32	23	57	40
Reclassification from AOCI, tax	(8)	(6)	(14)	(10)
Reclassification from AOCI, net	24	17	43	30
Total other comprehensive income (loss), before tax	(62)	99	(170)	493
Total other comprehensive income (loss), tax	15	(26)	42	(125)
Total other comprehensive income (loss), net	(47)	73	(128)	368
Defined benefit plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized gains (losses), net	0	0	0	0
Reclassification from AOCI, net	1	1	5	4
Total other comprehensive income (loss), before tax	1	2	6	6
Total other comprehensive income (loss), tax	0	(1)	(1)	(2)
Total other comprehensive income (loss), net	1	1	5	4
Net actuarial gain (loss) arising during the period
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized gains (losses), before tax	0	0	0	0
Net unrealized gains (losses), tax	0	0	0	0
Net unrealized gains (losses), net	0	0	0	0
Amortization of actuarial (gain) loss to earnings
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from AOCI	1	2	6	6
Reclassification from AOCI, tax	0	(1)	(1)	(2)
Reclassification from AOCI, net	$ 1	$ 1	$ 5	$ 4

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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