ACCUMULATED OTHER COMPREHENSIVE (LOSS) INCOME - Schedule of Changes in Components of AOCI (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, shareholders' equity	$ 22,295	$ 21,848	$ 22,228	$ 21,255
AOCI activity before reclassifications			334
Amounts reclassified from AOCI to earnings			(3)
Other comprehensive income (loss), net of tax	85	(28)	331	(119)
Ending balance, shareholders' equity	22,296	22,487	22,296	22,487
Total accumulated other comprehensive loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, shareholders' equity	(199)	(582)	(445)	(491)
Other comprehensive income (loss), net of tax	85	(28)	331	(119)
Ending balance, shareholders' equity	(114)	(610)	(114)	(610)
Unrealized loss on securities available for sale
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, shareholders' equity			(584)	(577)
AOCI activity before reclassifications			328
Amounts reclassified from AOCI to earnings			0
Other comprehensive income (loss), net of tax			328	(113)
Ending balance, shareholders' equity	(256)	(690)	(256)	(690)
Unrealized loss on securities available for sale transferred to held to maturity
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, shareholders' equity			(4)	(5)
AOCI activity before reclassifications			0
Amounts reclassified from AOCI to earnings			0
Other comprehensive income (loss), net of tax			0	0
Ending balance, shareholders' equity	(4)	(5)	(4)	(5)
Defined benefit pension items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, shareholders' equity			135	91
AOCI activity before reclassifications			(3)
Amounts reclassified from AOCI to earnings			0
Other comprehensive income (loss), net of tax	(3)	(8)	(3)	(8)
Ending balance, shareholders' equity	132	83	132	83
Unrealized gain on cash flow hedge derivatives
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, shareholders' equity			8	0
AOCI activity before reclassifications	(1)	2	9	2
Amounts reclassified from AOCI to earnings	0	0	(3)	0
Other comprehensive income (loss), net of tax	(1)	2	6	2
Ending balance, shareholders' equity	$ 14	$ 2	$ 14	$ 2