Goodwill (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Goodwill
Goodwill			$ 5,479
Accumulated impairment losses			(965)
Goodwill [Roll Forward]
Net carrying value, beginning of period	$ 4,915	$ 4,514
Acquisition activity	4	440
Reallocation of goodwill		0
Sale of businesses		(39)
Net carrying value, end of period	4,919	4,915
Operating Segments | Commercial Banking
Goodwill
Goodwill			2,730
Accumulated impairment losses			(750)
Goodwill [Roll Forward]
Net carrying value, beginning of period	2,324	1,980
Acquisition activity	0	0
Reallocation of goodwill		378
Sale of businesses		(34)
Net carrying value, end of period	2,324	2,324
Operating Segments | Consumer and Small Business Banking
Goodwill
Goodwill			2,518
Accumulated impairment losses			(215)
Goodwill [Roll Forward]
Net carrying value, beginning of period	2,365	2,303
Acquisition activity	4	440
Reallocation of goodwill		(378)
Sale of businesses		0
Net carrying value, end of period	2,369	2,365
Operating Segments | Wealth and Asset Management
Goodwill
Goodwill			231
Accumulated impairment losses			0
Goodwill [Roll Forward]
Net carrying value, beginning of period	226	231
Acquisition activity	0	0
Reallocation of goodwill		0
Sale of businesses		(5)
Net carrying value, end of period	226	226
General Corporate and Other
Goodwill
Goodwill			0
Accumulated impairment losses			$ 0
Goodwill [Roll Forward]
Net carrying value, beginning of period	0	0
Acquisition activity	0	0
Reallocation of goodwill		0
Sale of businesses		0
Net carrying value, end of period	$ 0	$ 0