Investment Securities (Gains And Losses, Including OTTI, Recognized In Statement Of Income) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Investments [Abstract]
Equity securities gains (losses)	$ 14	$ 7	$ 12
Investment securities, Available-for-sale, Gross gains	0	0	9
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net, Available-for-sale Securities	0	0	148
Other noninterest-bearing investments, Nonmarketable equity securities, Gross gains	22	21	25
Other noninterest-bearing investments, Nonmarketable equity securities, Gross losses	8	14	13
Total investment securities and other noninterest-bearing investments, Gross gains	22	21	34
Total investment securities and other noninterest-bearing investments, Gross losses	8	14	161
Net losses	14	7	(127)
Fixed income securities gains (losses), net	$ 0	$ 0	$ (139)