Asset Quality (Nonperforming Assets) (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Total nonperforming loans	$ 1,653	$ 1,694
OREO and Foreclosed Assets	132	114
Total nonperforming assets	$ 1,785	$ 1,808
Nonperforming loans to total loans	0.71%	0.75%
Nonperforming assets to total loans, OREO and foreclosed assets	0.77%	0.80%
Nonperforming assets to total assets	0.45%	0.47%
Total commercial lending [Member]
Total nonperforming loans	$ 430	$ 432
Total consumer lending [Member]
Total nonperforming loans	$ 1,223	$ 1,262