INVESTMENT SECURITIES - Schedule of Fair Values and Unrealized Losses of Impaired Securities, by Length of Impairment (Details) $ in Millions	Jun. 30, 2025 USD ($) security	Dec. 31, 2024 USD ($) security
Schedule Of Securities [Line Items]
Debt securities, available-for-sale, less than 12 months, number of positions \| security	12	43
Debt securities, available-for-sale, 12 months or longer, number of positions \| security	207	213
Debt securities, available-for-sale, number of positions \| security	219	256
Debt securities, available-for-sale, less than 12 months, fair value	$ 240	$ 1,104
Debt securities, available-for-sale, 12 months or longer, fair value	1,459	1,670
Debt securities, available-for-sale, fair value	1,699	2,774
Debt securities, available-for-sale, less than 12 months, unrealized losses	(1)	(10)
Debt securities, available-for-sale, 12 months or longer, unrealized losses	(108)	(148)
Debt securities, available-for-sale, unrealized losses	$ (109)	$ (158)
U.S. Treasury
Schedule Of Securities [Line Items]
Debt securities, available-for-sale, less than 12 months, number of positions \| security		3
Debt securities, available-for-sale, 12 months or longer, number of positions \| security		2
Debt securities, available-for-sale, number of positions \| security		5
Debt securities, available-for-sale, less than 12 months, fair value		$ 74
Debt securities, available-for-sale, 12 months or longer, fair value		75
Debt securities, available-for-sale, fair value		149
Debt securities, available-for-sale, less than 12 months, unrealized losses		(1)
Debt securities, available-for-sale, 12 months or longer, unrealized losses		0
Debt securities, available-for-sale, unrealized losses		$ (1)
U.S. government agencies
Schedule Of Securities [Line Items]
Debt securities, available-for-sale, less than 12 months, number of positions \| security	2	6
Debt securities, available-for-sale, 12 months or longer, number of positions \| security	10	12
Debt securities, available-for-sale, number of positions \| security	12	18
Debt securities, available-for-sale, less than 12 months, fair value	$ 3	$ 11
Debt securities, available-for-sale, 12 months or longer, fair value	21	25
Debt securities, available-for-sale, fair value	24	36
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	3	2
Debt securities, available-for-sale, 12 months or longer, number of positions \| security	6	7
Debt securities, available-for-sale, number of positions \| security	9	9
Debt securities, available-for-sale, less than 12 months, fair value	$ 75	$ 75
Debt securities, available-for-sale, 12 months or longer, fair value	103	126
Debt securities, available-for-sale, fair value	178	201
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)	(2)
Debt securities, available-for-sale, unrealized losses	$ (1)	$ (2)
Agency MBS
Schedule Of Securities [Line Items]
Debt securities, available-for-sale, less than 12 months, number of positions \| security	1	9
Debt securities, available-for-sale, 12 months or longer, number of positions \| security	92	92
Debt securities, available-for-sale, number of positions \| security	93	101
Debt securities, available-for-sale, less than 12 months, fair value	$ 0	$ 235
Debt securities, available-for-sale, 12 months or longer, fair value	302	355
Debt securities, available-for-sale, fair value	302	590
Debt securities, available-for-sale, less than 12 months, unrealized losses	0	(1)
Debt securities, available-for-sale, 12 months or longer, unrealized losses	(11)	(19)
Debt securities, available-for-sale, unrealized losses	$ (11)	$ (20)
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	66	66
Debt securities, available-for-sale, number of positions \| security	66	66
Debt securities, available-for-sale, less than 12 months, fair value	$ 0	$ 0
Debt securities, available-for-sale, 12 months or longer, fair value	652	698
Debt securities, available-for-sale, fair value	652	698
Debt securities, available-for-sale, less than 12 months, unrealized losses	0	0
Debt securities, available-for-sale, 12 months or longer, unrealized losses	(75)	(98)
Debt securities, available-for-sale, unrealized losses	$ (75)	$ (98)
Agency commercial MBS
Schedule Of Securities [Line Items]
Debt securities, available-for-sale, less than 12 months, number of positions \| security	6	23
Debt securities, available-for-sale, 12 months or longer, number of positions \| security	20	20
Debt securities, available-for-sale, number of positions \| security	26	43
Debt securities, available-for-sale, less than 12 months, fair value	$ 162	$ 709
Debt securities, available-for-sale, 12 months or longer, fair value	352	359
Debt securities, available-for-sale, fair value	514	1,068
Debt securities, available-for-sale, less than 12 months, unrealized losses	(1)	(8)
Debt securities, available-for-sale, 12 months or longer, unrealized losses	(19)	(27)
Debt securities, available-for-sale, unrealized losses	$ (20)	$ (35)
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	9	10
Debt securities, available-for-sale, number of positions \| security	9	10
Debt securities, available-for-sale, less than 12 months, fair value	$ 0	$ 0
Debt securities, available-for-sale, 12 months or longer, fair value	19	22
Debt securities, available-for-sale, fair value	19	22
Debt securities, available-for-sale, less than 12 months, unrealized losses	0	0
Debt securities, available-for-sale, 12 months or longer, unrealized losses	(2)	(2)
Debt securities, available-for-sale, unrealized losses	$ (2)	$ (2)
Other debt securities
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	4	4
Debt securities, available-for-sale, number of positions \| security	4	4
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	10
Debt securities, available-for-sale, fair value	10	10
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

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