Fair Value (Schedule Of Carrying Values And Estimated Fair Values Of Financial Instruments) (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Fair Value, Estimate Not Practicable, Financial Statement Captions [Line Items]
Held-to-maturity Securities	$ 746	$ 868
Held-to-maturity, fair value	743	850
Time deposits	2,909	2,757
Long-term debt (less fair value hedges)	383	535
Reported Value Measurement [Member]
Fair Value, Estimate Not Practicable, Financial Statement Captions [Line Items]
Loans and leases (including loans held for sale), net of allowance	43,686	42,254
Other Short-term Borrowings	3,250	500
Long-term debt (less fair value hedges)	383	535
Estimate of Fair Value Measurement [Member]
Fair Value, Estimate Not Practicable, Financial Statement Captions [Line Items]
Loans and leases (including loans held for sale), net of allowance	43,196	42,111
Time deposits	2,890	2,744
Other Short-term Borrowings	3,250	500
Long-term debt (less fair value hedges)	$ 406	$ 552