Investment Securities (Summary Of Investment Securities) (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Schedule of Investments [Line Items]
Amortized Cost	$ 20,351	$ 22,045
Gross Unrealized Gains	0	0
Gross Unrealized Losses	2,936	3,033
Fair Value	17,415	19,012
U.S. Treasury securities
Schedule of Investments [Line Items]
Amortized Cost	1,795	2,810
Gross Unrealized Gains	0	0
Gross Unrealized Losses	123	146
Fair Value	1,672	2,664
Residential mortgage-backed securities
Schedule of Investments [Line Items]
Amortized Cost	13,304	13,983
Gross Unrealized Gains	0	0
Gross Unrealized Losses	2,242	2,328
Fair Value	11,062	11,655
Commercial mortgage-backed securities
Schedule of Investments [Line Items]
Amortized Cost	5,252	5,252
Gross Unrealized Gains	0	0
Gross Unrealized Losses	571	559
Fair Value	$ 4,681	$ 4,693