ACCUMULATED OTHER COMPREHENSIVE (LOSS) INCOME - Schedule of Changes in Components of AOCI (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, shareholders' equity	$ 21,848	$ 19,216	$ 21,255	$ 9,662
AOCI activity before reclassifications				(50)
Amounts reclassified from AOCI to earnings				13
Other comprehensive loss, net of tax	(28)	(103)	(119)	(37)
Ending balance, shareholders' equity	22,487	19,771	22,487	19,771
Total accumulated other comprehensive loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, shareholders' equity	(582)	(669)	(491)	(735)
Other comprehensive loss, net of tax	(28)	(103)	(119)	(37)
Ending balance, shareholders' equity	(610)	(772)	(610)	(772)
Unrealized loss on securities available for sale
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, shareholders' equity			(577)	(739)
AOCI activity before reclassifications				(54)
Amounts reclassified from AOCI to earnings				12
Other comprehensive loss, net of tax			(113)	(42)
Ending balance, shareholders' equity	(690)	(781)	(690)	(781)
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			(5)	(6)
AOCI activity before reclassifications				0
Amounts reclassified from AOCI to earnings	0	1	0	1
Other comprehensive loss, net of tax	0	1	0	1
Ending balance, shareholders' equity	(5)	(5)	(5)	(5)
Defined benefit pension items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, shareholders' equity			91	10
AOCI activity before reclassifications				4
Amounts reclassified from AOCI to earnings				0
Other comprehensive loss, net of tax	(8)	(4)	(8)	4
Ending balance, shareholders' equity	83	14	83	14
Unrealized gain on cash flow hedge derivatives
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, shareholders' equity			0	0
AOCI activity before reclassifications				0
Amounts reclassified from AOCI to earnings				0
Other comprehensive loss, net of tax	2	0	2	0
Ending balance, shareholders' equity	$ 2	$ 0	$ 2	$ 0