Guarantees, Commitments And Contingencies (Schedule Of Guarantees Issued) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Guarantor Obligations [Line Items]
Unused Commitments to Extend Credit	$ 19,583	$ 18,274
Commercial letters of credit	31	60
Total Unfunded Lending Commitments	20,531	19,301
Financial Guarantee [Member]
Guarantor Obligations [Line Items]
Letters Of Credit Standby	721	771
Performance Guarantee [Member]
Guarantor Obligations [Line Items]
Letters Of Credit Standby	$ 196	$ 196