Investment Securities (Summary Of Investment Securities In Unrealized Loss Positions) (Details) - USD ($) $ in Millions		Jun. 30, 2021	Dec. 31, 2020
Temporarily Impaired Less than 12 months, Fair Value		$ 5,267	$ 2,071
Temporarily Impaired Less than 12 Months, Unrealized Losses		102	3
Temporarily Impaired 12 months or more, Fair Value		198	0
Temporarily Impaired 12 Months or more, Unrealized Losses		6	0
Temporarily Impaired Total, Fair Value		5,465	2,071
Temporarily Impaired Total, Unrealized Losses		108	3
U.S. Treasury and other U.S. government agency securities
Temporarily Impaired Less than 12 months, Fair Value		1,830	1,119
Temporarily Impaired Less than 12 Months, Unrealized Losses		21	1
Temporarily Impaired 12 months or more, Fair Value		0	0
Temporarily Impaired 12 Months or more, Unrealized Losses		0	0
Temporarily Impaired Total, Fair Value		1,830	1,119
Temporarily Impaired Total, Unrealized Losses		21	1
Residential mortgage-backed securities
Temporarily Impaired Less than 12 months, Fair Value	[1]	3,437	952
Temporarily Impaired Less than 12 Months, Unrealized Losses	[1]	81	2
Temporarily Impaired 12 months or more, Fair Value	[1]	198	0
Temporarily Impaired 12 Months or more, Unrealized Losses	[1]	6	0
Temporarily Impaired Total, Fair Value	[1]	3,635	952
Temporarily Impaired Total, Unrealized Losses	[1]	$ 87	$ 2

[1] Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.