INVESTMENT SECURITIES - Schedule of Fair Values and Unrealized Losses of Impaired Securities, by Length of Impairment (Details) $ in Millions	Jun. 30, 2026 USD ($) security	Dec. 31, 2025 USD ($) security
Schedule Of Securities [Line Items]
Debt securities, available-for-sale, less than 12 months, number of positions \| security	61	12
Debt securities, available-for-sale, 12 months or longer, number of positions \| security	192	203
Debt securities, available-for-sale, number of positions \| security	253	215
Debt securities, available-for-sale, less than 12 months, fair value	$ 1,226	$ 251
Debt securities, available-for-sale, 12 months or longer, fair value	1,153	1,322
Debt securities, available-for-sale, fair value	2,379	1,573
Debt securities, available-for-sale, less than 12 months, unrealized losses	(14)	(1)
Debt securities, available-for-sale, 12 months or longer, unrealized losses	(85)	(84)
Debt securities, available-for-sale, unrealized losses	$ (99)	$ (85)
U.S. Treasury
Schedule Of Securities [Line Items]
Debt securities, available-for-sale, less than 12 months, number of positions \| security	10
Debt securities, available-for-sale, 12 months or longer, number of positions \| security	0
Debt securities, available-for-sale, number of positions \| security	10
Debt securities, available-for-sale, less than 12 months, fair value	$ 252
Debt securities, available-for-sale, 12 months or longer, fair value	0
Debt securities, available-for-sale, fair value	252
Debt securities, available-for-sale, less than 12 months, unrealized losses	(2)
Debt securities, available-for-sale, 12 months or longer, unrealized losses	0
Debt securities, available-for-sale, unrealized losses	$ (2)
U.S. government agencies
Schedule Of Securities [Line Items]
Debt securities, available-for-sale, less than 12 months, number of positions \| security	9	5
Debt securities, available-for-sale, 12 months or longer, number of positions \| security	10	12
Debt securities, available-for-sale, number of positions \| security	19	17
Debt securities, available-for-sale, less than 12 months, fair value	$ 11	$ 8
Debt securities, available-for-sale, 12 months or longer, fair value	13	20
Debt securities, available-for-sale, fair value	24	28
Debt securities, available-for-sale, less than 12 months, unrealized losses	0	0
Debt securities, available-for-sale, 12 months or longer, unrealized losses	0	0
Debt securities, available-for-sale, unrealized losses	$ 0	$ 0
U.S. GSE
Schedule Of Securities [Line Items]
Debt securities, available-for-sale, less than 12 months, number of positions \| security	8	2
Debt securities, available-for-sale, 12 months or longer, number of positions \| security	2	3
Debt securities, available-for-sale, number of positions \| security	10	5
Debt securities, available-for-sale, less than 12 months, fair value	$ 213	$ 65
Debt securities, available-for-sale, 12 months or longer, fair value	26	51
Debt securities, available-for-sale, fair value	239	116
Debt securities, available-for-sale, less than 12 months, unrealized losses	(2)	0
Debt securities, available-for-sale, 12 months or longer, unrealized losses	0	0
Debt securities, available-for-sale, unrealized losses	$ (2)	$ 0
Agency MBS
Schedule Of Securities [Line Items]
Debt securities, available-for-sale, less than 12 months, number of positions \| security	8	1
Debt securities, available-for-sale, 12 months or longer, number of positions \| security	86	90
Debt securities, available-for-sale, number of positions \| security	94	91
Debt securities, available-for-sale, less than 12 months, fair value	$ 220	$ 46
Debt securities, available-for-sale, 12 months or longer, fair value	182	251
Debt securities, available-for-sale, fair value	402	297
Debt securities, available-for-sale, less than 12 months, unrealized losses	(4)	0
Debt securities, available-for-sale, 12 months or longer, unrealized losses	(8)	(8)
Debt securities, available-for-sale, unrealized losses	$ (12)	$ (8)
Agency CMO
Schedule Of Securities [Line Items]
Debt securities, available-for-sale, less than 12 months, number of positions \| security	0	0
Debt securities, available-for-sale, 12 months or longer, number of positions \| security	64	64
Debt securities, available-for-sale, number of positions \| security	64	64
Debt securities, available-for-sale, less than 12 months, fair value	$ 0	$ 0
Debt securities, available-for-sale, 12 months or longer, fair value	536	601
Debt securities, available-for-sale, fair value	536	601
Debt securities, available-for-sale, less than 12 months, unrealized losses	0	0
Debt securities, available-for-sale, 12 months or longer, unrealized losses	(63)	(61)
Debt securities, available-for-sale, unrealized losses	$ (63)	$ (61)
Agency commercial MBS
Schedule Of Securities [Line Items]
Debt securities, available-for-sale, less than 12 months, number of positions \| security	19	4
Debt securities, available-for-sale, 12 months or longer, number of positions \| security	21	22
Debt securities, available-for-sale, number of positions \| security	40	26
Debt securities, available-for-sale, less than 12 months, fair value	$ 489	$ 132
Debt securities, available-for-sale, 12 months or longer, fair value	377	371
Debt securities, available-for-sale, fair value	866	503
Debt securities, available-for-sale, less than 12 months, unrealized losses	(5)	(1)
Debt securities, available-for-sale, 12 months or longer, unrealized losses	(13)	(14)
Debt securities, available-for-sale, unrealized losses	$ (18)	$ (15)
States of the U.S. and political subdivisions (municipals)
Schedule Of Securities [Line Items]
Debt securities, available-for-sale, less than 12 months, number of positions \| security	0	0
Debt securities, available-for-sale, 12 months or longer, number of positions \| security	6	9
Debt securities, available-for-sale, number of positions \| security	6	9
Debt securities, available-for-sale, less than 12 months, fair value	$ 0	$ 0
Debt securities, available-for-sale, 12 months or longer, fair value	10	19
Debt securities, available-for-sale, fair value	10	19
Debt securities, available-for-sale, less than 12 months, unrealized losses	0	0
Debt securities, available-for-sale, 12 months or longer, unrealized losses	(1)	(1)
Debt securities, available-for-sale, unrealized losses	$ (1)	$ (1)
Other debt securities
Schedule Of Securities [Line Items]
Debt securities, available-for-sale, less than 12 months, number of positions \| security	7	0
Debt securities, available-for-sale, 12 months or longer, number of positions \| security	3	3
Debt securities, available-for-sale, number of positions \| security	10	3
Debt securities, available-for-sale, less than 12 months, fair value	$ 41	$ 0
Debt securities, available-for-sale, 12 months or longer, fair value	9	9
Debt securities, available-for-sale, fair value	50	9
Debt securities, available-for-sale, less than 12 months, unrealized losses	(1)	0
Debt securities, available-for-sale, 12 months or longer, unrealized losses	0	0
Debt securities, available-for-sale, unrealized losses	$ (1)	$ 0

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