Deposits and Borrowings - Long-Term Debt (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Total long-term debt	$ 36,676	$ 39,871
Total short-term borrowings and long-term debt	37,501	40,539
EUR denominated unsecured notes	23,983	27,382
Euro
Debt Instrument [Line Items]
EUR denominated unsecured notes	$ 1,500	1,600
Securitized debt obligations
Debt Instrument [Line Items]
Weighted average interest rate	1.64%
Carrying value	$ 12,635	12,414
Total senior and subordinated notes
Debt Instrument [Line Items]
Carrying value	$ 23,983	27,382
Senior notes \| Total unsecured senior debt
Debt Instrument [Line Items]
Weighted average interest rate	2.97%
Carrying value	$ 18,390	22,654
Senior notes \| Fixed unsecured senior debt
Debt Instrument [Line Items]
Weighted average interest rate	3.12%
Carrying value	$ 17,030	21,045
Senior notes \| Floating unsecured senior debt
Debt Instrument [Line Items]
Weighted average interest rate	1.05%
Carrying value	$ 1,360	1,609
Subordinated notes \| Fixed unsecured subordinated debt
Debt Instrument [Line Items]
Weighted average interest rate	3.52%
Carrying value	$ 5,593	4,728
Finance lease liabilities
Debt Instrument [Line Items]
Weighted average interest rate	3.14%
Carrying value	$ 58	75
Total other long-term borrowings
Debt Instrument [Line Items]
Carrying value	$ 58	$ 75
Minimum \| Securitized debt obligations
Debt Instrument [Line Items]
Stated interest rates	0.43%
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	0.85%
Minimum \| Subordinated notes \| Fixed unsecured subordinated debt
Debt Instrument [Line Items]
Stated interest rates	2.36%
Minimum \| Finance lease liabilities
Debt Instrument [Line Items]
Stated interest rates	0.30%
Maximum \| Securitized debt obligations
Debt Instrument [Line Items]
Stated interest rates	2.84%
Maximum \| Senior notes \| Fixed unsecured senior debt
Debt Instrument [Line Items]
Stated interest rates	4.25%
Maximum \| Senior notes \| Floating unsecured senior debt
Debt Instrument [Line Items]
Stated interest rates	1.28%
Maximum \| Subordinated notes \| Fixed unsecured subordinated debt
Debt Instrument [Line Items]
Stated interest rates	4.20%
Maximum \| Finance lease liabilities
Debt Instrument [Line Items]
Stated interest rates	9.91%

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

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