Investment Securities (Rollforward Of Total Amount Of Credit-Related OTTI) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Noninterest Income	$ 88	$ 86	$ 279	$ 257
Taxable [Member]
Noninterest Income	77	76	245	224
Nontaxable [Member]
Noninterest Income	11	10	34	33
Held-to-maturity Securities [Member]
Noninterest Income	6	7	18	19
Held-to-maturity Securities [Member] | Taxable [Member]
Noninterest Income	3	3	7	8
Held-to-maturity Securities [Member] | Nontaxable [Member]
Noninterest Income	3	4	11	11
Available-for-sale Securities [Member]
Noninterest Income	81	79	257	235
Available-for-sale Securities [Member] | Taxable [Member]
Noninterest Income	74	73	238	216
Available-for-sale Securities [Member] | Nontaxable [Member]
Noninterest Income	7	6	19	19
Other Trading [Member]
Noninterest Income	1	0	4	3
Other Trading [Member] | Taxable [Member]
Noninterest Income	0	0	0	0
Other Trading [Member] | Nontaxable [Member]
Noninterest Income	$ 1	$ 0	$ 4	$ 3