Business Segments - Results of Operations and Average Assets by Segment (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information
Net interest income	$ 1,438	$ 1,498	$ 4,411	$ 4,032
Provision for credit losses	119	158	460	383
Net Interest Income After Provision for Credit Losses	1,319	1,340	3,951	3,649
Noninterest Income
Commercial banking revenue	154	134	461	406
Wealth and asset management revenue	145	141	434	430
Service charges on deposits	149	143	431	449
Card and processing revenue	104	105	310	306
Mortgage banking net revenue	57	69	184	152
Leasing business revenue	58	60	162	179
Other noninterest income	55	59	152	195
Securities losses, net	(7)	(38)	3	(84)
Securities losses, net – non-qualifying hedges on MSRs	0	(1)	0	(2)
Total noninterest income	715	672	2,137	2,031
Noninterest Expense
Compensation and benefits	629	605	2,036	1,900
Technology and communications	115	106	347	306
Net occupancy expense(c)	84	74	248	225
Equipment expense	37	36	110	108
Marketing expense	35	35	96	87
Leasing business expense	29	33	94	95
Card and processing expense	21	21	63	59
Other noninterest expense	238	257	756	721
Total noninterest expense	1,188	1,167	3,750	3,501
Income (loss) before income taxes	846	845	2,338	2,179
Applicable income tax expense (benefit)	186	192	519	470
Net Income	660	653	1,819	1,709
Total goodwill	4,919	4,925	4,919	4,925	$ 4,915	$ 4,514
Total assets	212,967	205,463	212,967	205,463
Impairment losses on bank premises	0	1	2	2
Bank premises and equipment held for sale	22		22		24
Impairment losses and termination charges	1	0	2	2
Operating Segments | Commercial Banking
Segment Reporting Information
Net interest income	1,007	594	3,006	1,669
Provision for credit losses	0	(2)	37	44
Net Interest Income After Provision for Credit Losses	1,007	596	2,969	1,625
Noninterest Income
Commercial banking revenue	154	133	459	405
Wealth and asset management revenue	0	1	2	2
Service charges on deposits	95	90	275	285
Card and processing revenue	23	22	69	65
Mortgage banking net revenue	0	0	0	0
Leasing business revenue	58	60	162	179
Other noninterest income	24	24	68	88
Securities losses, net	(1)	(32)	(9)	(32)
Securities losses, net – non-qualifying hedges on MSRs	0	0	0	0
Total noninterest income	353	298	1,026	992
Noninterest Expense
Compensation and benefits	156	147	499	483
Technology and communications	4	2	10	9
Net occupancy expense(c)	12	10	32	30
Equipment expense	7	7	22	21
Marketing expense	1	1	2	3
Leasing business expense	29	33	94	95
Card and processing expense	3	3	8	8
Other noninterest expense	266	237	849	712
Total noninterest expense	478	440	1,516	1,361
Income (loss) before income taxes	882	454	2,479	1,256
Applicable income tax expense (benefit)	164	85	470	230
Net Income	718	369	2,009	1,026
Total goodwill	2,324	2,324	2,324	2,324	2,324	1,980
Total assets	82,829	83,798	82,829	83,798
Impairment losses of operating lease equipment				2
Operating Segments | Consumer and Small Business Banking
Segment Reporting Information
Net interest income	1,390	833	4,016	1,981
Provision for credit losses	105	34	221	93
Net Interest Income After Provision for Credit Losses	1,285	799	3,795	1,888
Noninterest Income
Commercial banking revenue	1	1	3	2
Wealth and asset management revenue	53	52	159	154
Service charges on deposits	55	53	159	164
Card and processing revenue	78	79	231	231
Mortgage banking net revenue	57	69	184	151
Leasing business revenue	0	0	0	0
Other noninterest income	30	33	83	86
Securities losses, net	0	0	0	0
Securities losses, net – non-qualifying hedges on MSRs	0	(1)	0	(2)
Total noninterest income	274	286	819	786
Noninterest Expense
Compensation and benefits	217	207	663	630
Technology and communications	7	6	20	15
Net occupancy expense(c)	52	49	156	147
Equipment expense	11	9	32	28
Marketing expense	17	20	52	44
Leasing business expense	0	0	0	0
Card and processing expense	19	19	57	54
Other noninterest expense	301	298	920	871
Total noninterest expense	624	608	1,900	1,789
Income (loss) before income taxes	935	477	2,714	885
Applicable income tax expense (benefit)	196	100	569	186
Net Income	739	377	2,145	699
Total goodwill	2,369	2,375	2,369	2,375	2,365	2,303
Total assets	88,230	84,653	88,230	84,653
Impairment losses on bank premises		1	1	2
Operating Segments | Wealth and Asset Management
Segment Reporting Information
Net interest income	98	79	294	167
Provision for credit losses	1	0	1	0
Net Interest Income After Provision for Credit Losses	97	79	293	167
Noninterest Income
Commercial banking revenue	0	1	1	1
Wealth and asset management revenue	137	132	410	407
Service charges on deposits	0	0	0	1
Card and processing revenue	0	1	2	2
Mortgage banking net revenue	0	0	0	1
Leasing business revenue	0	0	0	0
Other noninterest income	2	0	2	0
Securities losses, net	0	0	0	0
Securities losses, net – non-qualifying hedges on MSRs	0	0	0	0
Total noninterest income	139	134	415	412
Noninterest Expense
Compensation and benefits	53	54	169	166
Technology and communications	0	0	1	1
Net occupancy expense(c)	3	3	9	9
Equipment expense	0	0	0	0
Marketing expense	0	0	1	1
Leasing business expense	0	0	0	0
Card and processing expense	0	0	1	0
Other noninterest expense	79	85	242	244
Total noninterest expense	135	142	423	421
Income (loss) before income taxes	101	71	285	158
Applicable income tax expense (benefit)	22	15	59	33
Net Income	79	56	226	125
Total goodwill	226	226	226	226	$ 226	$ 231
Total assets	10,538	12,232	10,538	12,232
General Corporate and Other
Segment Reporting Information
Net interest income	(1,057)	(8)	(2,905)	215
Provision for credit losses	13	126	201	246
Net Interest Income After Provision for Credit Losses	(1,070)	(134)	(3,106)	(31)
Noninterest Income
Commercial banking revenue	(1)	(1)	(2)	(2)
Wealth and asset management revenue	0	0	0	0
Service charges on deposits	(1)	0	(3)	(1)
Card and processing revenue	3	3	8	8
Mortgage banking net revenue	0	0	0	0
Leasing business revenue	0	0	0	0
Other noninterest income	(1)	2	(1)	21
Securities losses, net	(6)	(6)	12	(52)
Securities losses, net – non-qualifying hedges on MSRs	0	0	0	0
Total noninterest income	(6)	(2)	14	(26)
Noninterest Expense
Compensation and benefits	203	197	705	621
Technology and communications	104	98	316	281
Net occupancy expense(c)	17	12	51	39
Equipment expense	19	20	56	59
Marketing expense	17	14	41	39
Leasing business expense	0	0	0	0
Card and processing expense	(1)	(1)	(3)	(3)
Other noninterest expense	(363)	(319)	(1,118)	(973)
Total noninterest expense	(4)	21	48	63
Income (loss) before income taxes	(1,072)	(157)	(3,140)	(120)
Applicable income tax expense (benefit)	(196)	(8)	(579)	21
Net Income	(876)	(149)	(2,561)	(141)
Total goodwill	0	0	0	0
Total assets	31,370	24,780	31,370	24,780
Impairment losses on bank premises			1
Bank premises and equipment held for sale	22	24	22	24
Eliminations
Segment Reporting Information
Net interest income	0	0	0	0
Provision for credit losses	0	0	0	0
Net Interest Income After Provision for Credit Losses	0	0	0	0
Noninterest Income
Commercial banking revenue	0	0	0	0
Wealth and asset management revenue	(45)	(44)	(137)	(133)
Service charges on deposits	0	0	0	0
Card and processing revenue	0	0	0	0
Mortgage banking net revenue	0	0	0	0
Leasing business revenue	0	0	0	0
Other noninterest income	0	0	0	0
Securities losses, net	0	0	0	0
Securities losses, net – non-qualifying hedges on MSRs	0	0	0	0
Total noninterest income	(45)	(44)	(137)	(133)
Noninterest Expense
Compensation and benefits	0	0	0	0
Technology and communications	0	0	0	0
Net occupancy expense(c)	0	0	0	0
Equipment expense	0	0	0	0
Marketing expense	0	0	0	0
Leasing business expense	0	0	0	0
Card and processing expense	0	0	0	0
Other noninterest expense	(45)	(44)	(137)	(133)
Total noninterest expense	(45)	(44)	(137)	(133)
Income (loss) before income taxes	0	0	0	0
Applicable income tax expense (benefit)	0	0	0	0
Net Income	0	0	0	0
Total goodwill	0	0	0	0
Total assets	$ 0	$ 0	$ 0	$ 0