Commitments, Guarantees, And Contingent Liabilities (Schedule Of Off Balance Sheet Financial Instruments) (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Net unfunded commitments to extend credit	$ 23,498	$ 23,099
Commercial letters of credit	21	5
Total unfunded lending commitments	24,229	23,927
Financial [Member]
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Standby letters of credit	532	631
Performance [Member]
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Standby letters of credit	$ 178	$ 192