Investments (Gains And Losses, Including OTTI, Recognized In Statement Of Income) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Investments [Abstract]
Other noninterest-bearing investments, Nonmarketable equity securities, Gross gains	$ 5	$ 2	$ 13	$ 7
Other noninterest-bearing investments, Nonmarketable equity securities, Gross losses	1	0	18	7
Net gains (losses)	$ 4	$ 2	$ (5)	$ 0