Commitments, Guarantees, and Contingent Liabilities (Schedule of Off Balance Sheet Financial Instruments) (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Net unfunded commitments to extend credit	$ 25,216	$ 24,217
Commercial letters of credit	39	34
Total unfunded lending commitments	26,138	24,949
Financial
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Standby letters of credit	649	531
Performance
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Standby letters of credit	$ 234	$ 167