Deposits and Borrowings - Long-Term Debt (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Total long-term debt	$ 48,725	$ 47,832
Total short-term borrowings and long-term debt	49,247	48,715
Time deposits, at or above FDIC insurance limit	15,400	6,100
Deposit Liability, Uninsured	8,500	2,000
Senior and subordinated notes	31,283	30,826
Euro
Debt Instrument [Line Items]
Senior and subordinated notes	$ 1,200	1,200
Securitized debt obligations
Debt Instrument [Line Items]
Weighted average interest rate	2.87%
Carrying value	$ 17,417	16,973
Total senior and subordinated notes
Debt Instrument [Line Items]
Carrying value	$ 31,283	30,826
Senior notes \| Total unsecured senior debt
Debt Instrument [Line Items]
Weighted average interest rate	4.11%
Carrying value	$ 27,667	25,731
Senior notes \| Fixed unsecured senior debt
Debt Instrument [Line Items]
Weighted average interest rate	4.01%
Carrying value	$ 26,419	24,134
Senior notes \| Floating unsecured senior debt
Debt Instrument [Line Items]
Weighted average interest rate	6.18%
Carrying value	$ 1,248	1,597
Subordinated notes \| Fixed unsecured subordinated debt
Debt Instrument [Line Items]
Weighted average interest rate	3.57%
Carrying value	$ 3,616	5,095
Other long-term borrowings
Debt Instrument [Line Items]
Carrying value	$ 25	$ 33
Other long-term borrowings \| Fixed unsecured subordinated debt
Debt Instrument [Line Items]
Weighted average interest rate	6.38%
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 \| Senior notes \| Floating unsecured senior debt
Debt Instrument [Line Items]
Stated interest rates	6.00%
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	0.35%
Maximum \| Securitized debt obligations
Debt Instrument [Line Items]
Stated interest rates	6.12%
Maximum \| Senior notes \| Fixed unsecured senior debt
Debt Instrument [Line Items]
Stated interest rates	6.38%
Maximum \| Senior notes \| Floating unsecured senior debt
Debt Instrument [Line Items]
Stated interest rates	6.66%
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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