Asset Quality (Nonperforming Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Total nonperforming loans	$ 1,694	$ 1,865
OREO and Foreclosed Assets	114	170
Total nonperforming assets	$ 1,808	$ 2,035
Nonperforming loans to total loans	0.75%	0.85%
Nonperforming assets to total loans, OREO and foreclosed assets	0.80%	0.92%
Nonperforming assets to total assets	0.47%	0.53%
Interest on nonperforming loans - Computed on original terms	$ 123	$ 114
Interest on nonperforming loans - Recognized prior to nonperforming status	17	19
Total commercial lending
Total nonperforming loans	432	554
Total consumer lending
Total nonperforming loans	$ 1,262	$ 1,311