Derivative And Credit-Related Financial Instruments (Schedule Of Financial Instruments With Off-Balance Sheet Credit Risk) (Details) - Maximum - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Unused Commitments to Extend Credit
Loss contingency, estimate of possible loss, maximum	$ (26,581)	$ (25,469)
Commercial And Other | Unused Commitments to Extend Credit
Loss contingency, estimate of possible loss, maximum	(23,591)	(22,636)
Bankcard, Revolving Check Credit And Home Equity Loan Commitments | Unused Commitments to Extend Credit
Loss contingency, estimate of possible loss, maximum	(2,990)	(2,833)
Standby Letters Of Credit
Loss contingency, estimate of possible loss, maximum	(3,228)	(3,228)
Commercial Letters Of Credit
Loss contingency, estimate of possible loss, maximum	$ (34)	$ (39)