ACCUMULATED OTHER COMPREHENSIVE (LOSS) INCOME - Schedule of Pretax and After-tax Components of Other Comprehensive Income (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]
AOCI activity before reclassification, Net of Income Taxes			$ (310)	$ 334
Amounts reclassified from AOCI to earnings, Net of Income Taxes			(3)	(3)
Other comprehensive (loss) income on securities available for sale and cash flow hedges, Pretax	$ (212)	$ 114	(420)	445
Other comprehensive (loss) income on securities available for sale and cash flow hedges, Income Taxes	54	(29)	107	(114)
Other comprehensive income (loss) for the period	(158)	85	(313)	331
Unrealized loss on securities available for sale:
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive (loss) income on securities available for sale and cash flow hedges, Pretax	(178)	119	(365)	441
Other comprehensive (loss) income on securities available for sale and cash flow hedges, Income Taxes	45	(30)	93	(113)
Other comprehensive income (loss) for the period	(133)	89	(272)	328
Defined benefit pension items
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI activity before reclassification, Pretax	(3)	(4)	(5)	(4)
AOCI activity before reclassification, Income Taxes	1	1	1	1
AOCI activity before reclassification, Net of Income Taxes	(2)	(3)	(4)	(3)
Amounts reclassified from AOCI to earnings, Pretax	(1)	0	(1)	0
Amounts reclassified from AOCI to earnings, Income Taxes	0	0	0	0
Amounts reclassified from AOCI to earnings, Net of Income Taxes	(1)	0	(1)	0
Other comprehensive (loss) income on securities available for sale and cash flow hedges, Pretax	(4)	(4)	(6)	(4)
Other comprehensive (loss) income on securities available for sale and cash flow hedges, Income Taxes	1	1	1	1
Other comprehensive income (loss) for the period	(3)	(3)	(5)	(3)
Unrealized gain (loss) on cash flow hedge derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI activity before reclassification, Pretax	(28)	0	(47)	12
AOCI activity before reclassification, Income Taxes	8	(1)	13	(3)
AOCI activity before reclassification, Net of Income Taxes	(20)	(1)	(34)	9
Amounts reclassified from AOCI to earnings, Pretax	(2)	(1)	(2)	(4)
Amounts reclassified from AOCI to earnings, Income Taxes	0	1	0	1
Amounts reclassified from AOCI to earnings, Net of Income Taxes	(2)	0	(2)	(3)
Other comprehensive (loss) income on securities available for sale and cash flow hedges, Pretax	(30)	(1)	(49)	8
Other comprehensive (loss) income on securities available for sale and cash flow hedges, Income Taxes	8	0	13	(2)
Other comprehensive income (loss) for the period	$ (22)	$ (1)	$ (36)	$ 6

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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