Investment Securities (Rollforward Of Total Amount Of Credit-Related OTTI) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Noninterest Income	$ 95	$ 85	$ 191	$ 170
Taxable [Member]
Noninterest Income	83	73	168	147
Nontaxable [Member]
Noninterest Income	12	12	23	23
Held-to-maturity Securities [Member]
Noninterest Income	6	6	12	12
Held-to-maturity Securities [Member] | Taxable [Member]
Noninterest Income	2	3	4	5
Held-to-maturity Securities [Member] | Nontaxable [Member]
Noninterest Income	4	3	8	7
Available-for-sale Securities [Member]
Noninterest Income	87	77	176	155
Available-for-sale Securities [Member] | Taxable [Member]
Noninterest Income	81	70	164	142
Available-for-sale Securities [Member] | Nontaxable [Member]
Noninterest Income	6	7	12	13
Other Trading [Member]
Noninterest Income	2	2	3	3
Other Trading [Member] | Taxable [Member]
Noninterest Income	0	0	0	0
Other Trading [Member] | Nontaxable [Member]
Noninterest Income	$ 2	$ 2	$ 3	$ 3