Accumulated Other Comprehensive Income - Schedule of Reclassifications Out of AOCI (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest income — Loans	$ 1,576	$ 923	$ 3,052	$ 1,760
Interest expense — Long-term debt	(349)	(61)	(624)	(110)
Investment banking and debt placement fees	120	149	265	312
Other expense	622	607	1,323	1,237
Income taxes	58	132	139	222
INCOME (LOSS) FROM CONTINUING OPERATIONS	286	530	597	977
Reclassification out of Accumulated Other Comprehensive Income | Unrealized gains (losses) on derivative financial instruments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Investment banking and debt placement fees	0	5	0	7
Other expense			(5)	(7)
Income (loss) from continuing operations before income taxes	(246)	23	(461)	87
Income taxes	(58)	5	(109)	21
INCOME (LOSS) FROM CONTINUING OPERATIONS	(188)	18	(352)	66
Reclassification out of Accumulated Other Comprehensive Income | Unrealized gains (losses) on derivative financial instruments | Interest income — Loans
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest income — Loans	(245)	19	(460)	82
Reclassification out of Accumulated Other Comprehensive Income | Unrealized gains (losses) on derivative financial instruments | Interest expense — Long-term debt
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense — Long-term debt	(1)	(1)	(1)	(2)
Reclassification out of Accumulated Other Comprehensive Income | Amortization of losses
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other expense	(2)	(3)
Reclassification out of Accumulated Other Comprehensive Income | Settlement loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other expense	0	0	0	0
Reclassification out of Accumulated Other Comprehensive Income | Amortization of unrecognized prior service credit
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other expense	0	1	1	1
Reclassification out of Accumulated Other Comprehensive Income | Net pension and postretirement benefit costs
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income (loss) from continuing operations before income taxes	(2)	(2)	(4)	(6)
Income taxes	0	0	(1)	(1)
INCOME (LOSS) FROM CONTINUING OPERATIONS	$ (2)	$ (2)	$ (3)	$ (5)