Fair Value (Schedule Of Carrying Values And Estimated Fair Values Of Financial Instruments) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Fair Value, Estimate Not Practicable, Financial Statement Captions [Line Items]
Held-to-maturity Securities	$ 815	$ 868
Held-to-maturity, fair value	803	850
Time deposits	2,994	2,757
Interest-bearing Deposit Liabilities, Foreign	0	0
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	42,326	42,254
Other Short-term Borrowings	2,500	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	42,038	42,111
Time deposits	2,977	2,744
Other Short-term Borrowings	2,500	500
Long-term debt (less fair value hedges)	$ 404	$ 552