ACCUMULATED OTHER COMPREHENSIVE (LOSS) INCOME - Schedule of Changes in Components of AOCI (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, shareholders' equity	$ 22,296	$ 22,487	$ 22,228	$ 21,255
AOCI activity before reclassifications			404	329
Amounts reclassified from AOCI to earnings			(3)	3
Other comprehensive income, net of tax	70	451	401	332
Ending balance, shareholders' equity	21,986	22,828	21,986	22,828
Total accumulated other comprehensive loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, shareholders' equity	(114)	(610)	(445)	(491)
Other comprehensive income, net of tax	70	451	401	332
Ending balance, shareholders' equity	(44)	(159)	(44)	(159)
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			400	325
Amounts reclassified from AOCI to earnings			0	0
Other comprehensive income, net of tax			400	325
Ending balance, shareholders' equity	(184)	(252)	(184)	(252)
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	0
Amounts reclassified from AOCI to earnings	0	1	0	1
Other comprehensive income, net of tax			0	1
Ending balance, shareholders' equity	(4)	(4)	(4)	(4)
Defined benefit pension items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, shareholders' equity			135	91
AOCI activity before reclassifications			(4)	(8)
Amounts reclassified from AOCI to earnings			0	0
Other comprehensive income, net of tax	(1)	0	(4)	(8)
Ending balance, shareholders' equity	131	83	131	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)	10	8	12
Amounts reclassified from AOCI to earnings	0	2	(3)	2
Other comprehensive income, net of tax	(1)	12	5	14
Ending balance, shareholders' equity	$ 13	$ 14	$ 13	$ 14