Investment Securities (Summary Of Investment Securities) (Details) - USD ($) $ in Millions		Mar. 31, 2023	Dec. 31, 2022
Amortized Cost		$ 21,019	$ 22,045
Gross Unrealized Gains		0	0
Gross Unrealized Losses		2,724	3,033
Fair Value		18,295	19,012
U.S. Treasury securities
Amortized Cost		2,103	2,810
Gross Unrealized Gains		0	0
Gross Unrealized Losses		119	146
Fair Value		1,984	2,664
Residential mortgage-backed securities
Amortized Cost	[1]	13,665	13,983
Gross Unrealized Gains	[1]	0	0
Gross Unrealized Losses	[1]	2,134	2,328
Fair Value	[1]	11,531	11,655
Commercial mortgage-backed securities
Amortized Cost	[1]	5,251	5,252
Gross Unrealized Gains	[1]	0	0
Gross Unrealized Losses	[1]	471	559
Fair Value	[1]	$ 4,780	$ 4,693

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