Deposits and Borrowings - Long-Term Debt (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Total long-term debt	$ 49,318	$ 47,832
Total short-term borrowings and long-term debt	49,856	48,715
Time deposits, at or above FDIC insurance limit	15,800	6,100
Deposit liability, uninsured	9,000	2,000
Senior and subordinated notes	31,248	30,826
Euro
Debt Instrument [Line Items]
Senior and subordinated notes	$ 1,300	1,200
Securitized debt obligations
Debt Instrument [Line Items]
Weighted-Average Interest Rate	3.01%
Carrying value	$ 18,043	16,973
Total senior and subordinated notes
Debt Instrument [Line Items]
Carrying value	$ 31,248	30,826
Senior notes \| Total unsecured senior debt
Debt Instrument [Line Items]
Weighted-Average Interest Rate	4.48%
Carrying value	$ 27,517	25,731
Senior notes \| Fixed unsecured senior debt
Debt Instrument [Line Items]
Weighted-Average Interest Rate	4.45%
Carrying value	$ 27,168	24,134
Senior notes \| Floating unsecured senior debt
Debt Instrument [Line Items]
Weighted-Average Interest Rate	6.75%
Carrying value	$ 349	1,597
Subordinated notes \| Fixed unsecured subordinated debt
Debt Instrument [Line Items]
Weighted-Average Interest Rate	3.57%
Carrying value	$ 3,731	5,095
Other long-term borrowings
Debt Instrument [Line Items]
Weighted-Average Interest Rate	6.51%
Carrying value	$ 27	$ 33
Minimum \| Securitized debt obligations
Debt Instrument [Line Items]
Stated Interest Rates	0.55%
Minimum \| Senior notes \| Fixed unsecured senior debt
Debt Instrument [Line Items]
Stated Interest Rates	0.80%
Minimum \| Subordinated notes \| Fixed unsecured subordinated debt
Debt Instrument [Line Items]
Stated Interest Rates	2.36%
Minimum \| Other long-term borrowings
Debt Instrument [Line Items]
Stated Interest Rates	0.36%
Maximum \| Securitized debt obligations
Debt Instrument [Line Items]
Stated Interest Rates	6.21%
Maximum \| Senior notes \| Fixed unsecured senior debt
Debt Instrument [Line Items]
Stated Interest Rates	7.62%
Maximum \| Senior notes \| Floating unsecured senior debt
Debt Instrument [Line Items]
Stated Interest Rates	6.75%
Maximum \| Subordinated notes \| Fixed unsecured subordinated debt
Debt Instrument [Line Items]
Stated Interest Rates	4.20%
Maximum \| Other long-term borrowings
Debt Instrument [Line Items]
Stated Interest Rates	9.91%

Amount of short-term and long-term debt and lease obligation.

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