Commitments, Guarantees, And Contingent Liabilities (Schedule Of Guarantees Issued) (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Unused Commitments to Extend Credit	$ 18,828	$ 18,274
Commercial Letters Of Credit	43	60
Total Unfunded Lending Commitments	19,782	19,301
Financial [Member]
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Standby letters of credit	709	771
Performance [Member]
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Standby letters of credit	202	$ 196
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	$ 20