Commitments, Guarantees, And Contingent Liabilities (Schedule Of Off Balance Sheet Financial Instruments) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Net unfunded commitments to extend credit	$ 24,123	$ 23,099
Commercial letters of credit	14	5
Total unfunded lending commitments	24,845	23,927
Financial
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Standby letters of credit	526	631
Performance
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Standby letters of credit	$ 182	$ 192