Derivative And Credit-Related Financial Instruments (Schedule Of Financial Instruments With Off-Balance Sheet Credit Risk) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Document Period End Date	Dec. 31, 2019
Maximum | Unused Commitments to Extend Credit
Loss contingency, estimate of possible loss, maximum	$ 26,861	$ 27,267
Maximum | Commercial And Other | Unused Commitments to Extend Credit
Loss contingency, estimate of possible loss, maximum	23,681	24,266
Maximum | Bankcard, Revolving Check Credit And Home Equity Loan Commitments | Unused Commitments to Extend Credit
Loss contingency, estimate of possible loss, maximum	3,180	3,001
Maximum | Standby Letters Of Credit
Loss contingency, estimate of possible loss, maximum	3,320	3,244
Maximum | Commercial Letters Of Credit
Loss contingency, estimate of possible loss, maximum	$ 18	$ 39