Derivative And Credit-Related Financial Instruments (Schedule Of Net Gains Recognized In Income On Customer-Initiated Derivatives) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Document Period End Date	Dec. 31, 2019
Customer-initiated and other activities
Derivative Instruments, Gain (Loss) [Line Items]
Net derivative gain recognized in income	$ 77	$ 77
Interest rate contracts | Customer-initiated and other activities | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Net derivative gain recognized in income	29	26
Energy contracts | Customer-initiated and other activities | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Net derivative gain recognized in income	5	4
Foreign exchange contracts | Customer-initiated and other activities | Foreign exchange income
Derivative Instruments, Gain (Loss) [Line Items]
Net derivative gain recognized in income	$ 43	$ 47