Derivative And Credit-Related Financial Instruments (Schedule Of Financial Instruments With Off-Balance Sheet Credit Risk) (Details) - Maximum - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Unused Commitments to Extend Credit
Loss contingency, estimate of possible loss	$ 26,598	$ 26,861
Commercial And Other | Unused Commitments to Extend Credit
Loss contingency, estimate of possible loss	23,322	23,681
Bankcard, Revolving Check Credit And Home Equity Loan Commitments | Unused Commitments to Extend Credit
Loss contingency, estimate of possible loss	3,276	3,180
Standby Letters Of Credit
Loss contingency, estimate of possible loss	3,191	3,320
Commercial Letters Of Credit
Loss contingency, estimate of possible loss	$ 26	$ 18