Goodwill and Other Intangible Assets - Schedule of Gross Goodwill And Accumulated Impairment Losses And Write-Offs Detailed By Reportable Segments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Goodwill [Roll Forward]
Goodwill, Beginning balance	$ 1,511	$ 1,511	$ 1,511
Additions	0	0	0
Divestitures	(1)
Goodwill, Ending balance	1,510	1,511	1,511
Regional Banking
Goodwill [Roll Forward]
Goodwill, Beginning balance	880	880	880
Additions	0	0	0
Divestitures	0
Goodwill, Ending balance	880	880	880
Specialty Banking
Goodwill [Roll Forward]
Goodwill, Beginning balance	631	631	631
Additions	0	0	0
Divestitures	(1)
Goodwill, Ending balance	$ 630	$ 631	$ 631