Business Segments - Results of Operations and Average Assets by Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information
Total goodwill	$ 4,514	$ 4,258	$ 4,252
Total assets	211,116	204,680	169,369
Net interest income	4,770	4,782	4,797
(Benefit from) provision for credit losses	(377)	1,097	471
Net Interest Income After (Benefit from) Provision for Credit Losses	5,147	3,685	4,326
Noninterest income:
Commercial banking revenue	637	528	460
Service charges on deposits	600	559	565
Wealth and asset management revenue	586	520	487
Card and processing revenue	402	352	360
Leasing business revenue	300	276	270
Mortgage banking net revenue	270	320	287
Other noninterest income	332	211	1,064
Securities (losses) gains, net	(7)	62	40
Securities losses, net -non-qualifying hedges on MSRs	(2)	2	3
Total noninterest income	3,118	2,830	3,536
Noninterest expense:
Compensation and benefits	2,626	2,590	2,418
Technology and communications	388	362	422
Net occupancy expense	312	350	332
Equipment expense	138	130	129
Leasing business expense	137	140	133
Marketing expense	107	104	162
Card and processing expense	89	121	130
Other noninterest expense	951	921	934
Total noninterest expense	4,748	4,718	4,660
Income before income taxes	3,517	1,797	3,202
Applicable income tax expense	747	370	690
Net Income	2,770	1,427	2,512
Impairment losses on bank premises	7	30	28
Impairment losses and termination charges	3	8	15
Bank premises and equipment held for sale	24	35
Commercial Banking
Segment Reporting Information
Total goodwill	1,980	1,980	1,954
Branch Banking
Segment Reporting Information
Total goodwill	2,303	2,047	2,046
Consumer Lending
Segment Reporting Information
Total goodwill	0	0	0
Wealth and Asset Management
Segment Reporting Information
Total goodwill	231	231	252
Operating Segments | Commercial Banking
Segment Reporting Information
Total goodwill	1,980	1,980	1,954
Total assets	73,306	70,241	74,570
Net interest income	1,498	1,903	2,360
(Benefit from) provision for credit losses	(583)	1,050	183
Net Interest Income After (Benefit from) Provision for Credit Losses	2,081	853	2,177
Noninterest income:
Commercial banking revenue	626	524	455
Service charges on deposits	363	343	308
Wealth and asset management revenue	2	3	3
Card and processing revenue	61	54	66
Leasing business revenue	300	276	270
Mortgage banking net revenue	0	0	0
Other noninterest income	87	101	85
Securities (losses) gains, net	8	0	0
Securities losses, net -non-qualifying hedges on MSRs	0	0	0
Total noninterest income	1,447	1,301	1,187
Noninterest expense:
Compensation and benefits	586	557	466
Technology and communications	17	13	11
Net occupancy expense	33	31	28
Equipment expense	26	27	25
Leasing business expense	137	140	133
Marketing expense	7	8	12
Card and processing expense	6	7	8
Other noninterest expense	843	938	938
Total noninterest expense	1,655	1,721	1,621
Income before income taxes	1,873	433	1,743
Applicable income tax expense	354	46	319
Net Income	1,519	387	1,424
Impairment losses of operating lease equipment	25	7	3
Operating Segments | Branch Banking
Segment Reporting Information
Total goodwill	2,303	2,047	2,046
Total assets	92,079	79,982	69,413
Net interest income	1,221	1,667	2,371
(Benefit from) provision for credit losses	97	231	224
Net Interest Income After (Benefit from) Provision for Credit Losses	1,124	1,436	2,147
Noninterest income:
Commercial banking revenue	9	5	4
Service charges on deposits	236	215	260
Wealth and asset management revenue	206	172	158
Card and processing revenue	329	283	285
Leasing business revenue	0	0	0
Mortgage banking net revenue	10	8	6
Other noninterest income	103	68	89
Securities (losses) gains, net	0	0	0
Securities losses, net -non-qualifying hedges on MSRs	0	0	0
Total noninterest income	893	751	802
Noninterest expense:
Compensation and benefits	646	649	601
Technology and communications	5	4	4
Net occupancy expense	191	176	173
Equipment expense	38	41	48
Leasing business expense	0	0	0
Marketing expense	38	32	72
Card and processing expense	86	116	123
Other noninterest expense	870	851	839
Total noninterest expense	1,874	1,869	1,860
Income before income taxes	143	318	1,089
Applicable income tax expense	29	67	229
Net Income	114	251	860
Impairment losses on bank premises	6	15	11
Operating Segments | Consumer Lending
Segment Reporting Information
Total goodwill	0	0	0
Total assets	33,270	30,480	26,555
Net interest income	562	381	325
(Benefit from) provision for credit losses	9	34	49
Net Interest Income After (Benefit from) Provision for Credit Losses	553	347	276
Noninterest income:
Commercial banking revenue	0	0	0
Service charges on deposits	0	0	0
Wealth and asset management revenue	0	0	0
Card and processing revenue	0	0	0
Leasing business revenue	0	0	0
Mortgage banking net revenue	257	307	279
Other noninterest income	9	10	14
Securities (losses) gains, net	0	0	0
Securities losses, net -non-qualifying hedges on MSRs	(2)	2	3
Total noninterest income	264	319	296
Noninterest expense:
Compensation and benefits	245	221	196
Technology and communications	11	8	8
Net occupancy expense	10	10	10
Equipment expense	0	0	0
Leasing business expense	0	0	0
Marketing expense	3	3	4
Card and processing expense	0	0	0
Other noninterest expense	370	276	237
Total noninterest expense	639	518	455
Income before income taxes	178	148	117
Applicable income tax expense	37	31	25
Net Income	141	117	92
Operating Segments | Wealth and Asset Management
Segment Reporting Information
Total goodwill	231	231	252
Total assets	13,836	12,466	10,500
Net interest income	88	139	182
(Benefit from) provision for credit losses	(1)	3	0
Net Interest Income After (Benefit from) Provision for Credit Losses	89	136	182
Noninterest income:
Commercial banking revenue	2	2	1
Service charges on deposits	1	1	1
Wealth and asset management revenue	558	498	469
Card and processing revenue	2	2	3
Leasing business revenue	0	0	0
Mortgage banking net revenue	3	5	2
Other noninterest income	4	18	13
Securities (losses) gains, net	0	0	0
Securities losses, net -non-qualifying hedges on MSRs	0	0	0
Total noninterest income	570	526	489
Noninterest expense:
Compensation and benefits	205	218	217
Technology and communications	1	1	1
Net occupancy expense	15	12	13
Equipment expense	0	1	1
Leasing business expense	0	0	0
Marketing expense	2	2	5
Card and processing expense	1	1	1
Other noninterest expense	316	298	291
Total noninterest expense	540	533	529
Income before income taxes	119	129	142
Applicable income tax expense	25	27	30
Net Income	94	102	112
General Corporate and Other
Segment Reporting Information
Total goodwill	0	0	0
Total assets	(1,375)	11,511	(11,669)
Net interest income	1,401	692	(441)
(Benefit from) provision for credit losses	101	(221)	15
Net Interest Income After (Benefit from) Provision for Credit Losses	1,300	913	(456)
Noninterest income:
Commercial banking revenue	0	(3)	0
Service charges on deposits	0	0	(4)
Wealth and asset management revenue	0	0	0
Card and processing revenue	10	13	6
Leasing business revenue	0	0	0
Mortgage banking net revenue	0	0	0
Other noninterest income	129	14	863
Securities (losses) gains, net	(15)	62	40
Securities losses, net -non-qualifying hedges on MSRs	0	0	0
Total noninterest income	124	86	905
Noninterest expense:
Compensation and benefits	944	945	938
Technology and communications	354	336	398
Net occupancy expense	63	121	108
Equipment expense	74	61	55
Leasing business expense	0	0	0
Marketing expense	57	59	69
Card and processing expense	(4)	(3)	(2)
Other noninterest expense	(1,268)	(1,289)	(1,228)
Total noninterest expense	220	230	338
Income before income taxes	1,204	769	111
Applicable income tax expense	302	199	87
Net Income	902	570	24
Impairment losses on bank premises	1	15	17
Bank premises and equipment held for sale	24	35	27
Eliminations
Segment Reporting Information
Total goodwill	0	0	0
Total assets	0	0	0
Net interest income	0	0	0
(Benefit from) provision for credit losses	0	0	0
Net Interest Income After (Benefit from) Provision for Credit Losses	0	0	0
Noninterest income:
Commercial banking revenue	0	0	0
Service charges on deposits	0	0	0
Wealth and asset management revenue	(180)	(153)	(143)
Card and processing revenue	0	0	0
Leasing business revenue	0	0	0
Mortgage banking net revenue	0	0	0
Other noninterest income	0	0	0
Securities (losses) gains, net	0	0	0
Securities losses, net -non-qualifying hedges on MSRs	0	0	0
Total noninterest income	(180)	(153)	(143)
Noninterest expense:
Compensation and benefits	0	0	0
Technology and communications	0	0	0
Net occupancy expense	0	0	0
Equipment expense	0	0	0
Leasing business expense	0	0	0
Marketing expense	0	0	0
Card and processing expense	0	0	0
Other noninterest expense	(180)	(153)	(143)
Total noninterest expense	(180)	(153)	(143)
Income before income taxes	0	0	0
Applicable income tax expense	0	0	0
Net Income	$ 0	$ 0	$ 0