ACCUMULATED OTHER COMPREHENSIVE (LOSS) INCOME - Schedule of Changes in Components of AOCI (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, shareholders' equity	$ 22,487	$ 19,771	$ 21,255	$ 9,662
AOCI activity before reclassifications			329	(165)
Amounts reclassified from AOCI to earnings			3	20
Other comprehensive income (loss), net of tax	451	(108)	332	(145)
Ending balance, shareholders' equity	22,828	20,389	22,828	20,389
Total accumulated other comprehensive loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, shareholders' equity	(610)	(772)	(491)	(735)
Other comprehensive income (loss), net of tax	451	(108)	332	(145)
Ending balance, shareholders' equity	(159)	(880)	(159)	(880)
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			325	(169)
Amounts reclassified from AOCI to earnings			0	19
Other comprehensive income (loss), net of tax			325	(150)
Ending balance, shareholders' equity	(252)	(889)	(252)	(889)
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	0
Amounts reclassified from AOCI to earnings	1	0	1	1
Other comprehensive income (loss), net of tax	1	0	1	1
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			91	10
AOCI activity before reclassifications			(8)	4
Amounts reclassified from AOCI to earnings			0	0
Other comprehensive income (loss), net of tax			(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	10	0	12	0
Amounts reclassified from AOCI to earnings	2	0	2	0
Other comprehensive income (loss), net of tax	12	0	14	0
Ending balance, shareholders' equity	$ 14	$ 0	$ 14	$ 0