Asset Quality (Nonperforming Assets) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Total nonperforming loans	$ 1,728	$ 1,694
OREO and Foreclosed Assets	119	114
Total nonperforming assets	$ 1,847	$ 1,808
Nonperforming loans to total loans	0.73%	0.75%
Nonperforming assets to total loans, OREO and foreclosed assets	0.78%	0.80%
Nonperforming assets to total assets	0.45%	0.47%
Total commercial lending [Member]
Total nonperforming loans	$ 576	$ 432
Total consumer lending [Member]
Total nonperforming loans	$ 1,152	$ 1,262