Commitments, Guarantees, And Contingent Liabilities (Schedule Of Guarantees Issued) (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Unused Commitments to Extend Credit	$ 21,632	$ 21,454
Commercial Letters Of Credit	27	18
Total Unfunded Lending Commitments	22,399	22,326
Financial [Member]
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Standby letters of credit	544	655
Performance [Member]
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Standby letters of credit	196	$ 199
Minimum [Member]
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Loss Contingency, Estimate of Possible Loss	0
Maximum [Member]
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Loss Contingency, Estimate of Possible Loss	$ 50