Business Segments - Results of Operations and Average Assets by Segment (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information
Total goodwill		$ 4,261	$ 4,290	$ 4,261	$ 4,290	$ 4,252	$ 2,478
Total assets		201,996	171,079	201,996	171,079
Net interest income		1,170	1,242	3,600	3,569
Provision for (benefit from) credit losses		(15)	134	1,110	310
Net Interest Income After Provision for (Benefit from) Credit Losses		1,185	1,108	2,490	3,259
Noninterest Income:
Service charges on deposits	[1]	144	143	414	417
Wealth and asset management revenue	[1]	132	124	387	358
Commercial banking revenue	[1]	125	123	387	333
Mortgage banking net revenue	[1]	76	95	295	214
Card and processing revenue	[1]	92	94	260	266
Leasing business revenue	[1]	77	92	207	199
Other noninterest income	[1]	26	64	42	679
Securities gains, net	[1]	51	5	48	30
Securities losses, net – non-qualifying hedges on MSRs	[1]	(1)	0	3	5
Total noninterest income	[1]	722	740	2,043	2,501
Noninterest expense:
Compensation and benefits	[1]	637	584	1,911	1,843
Technology and communications	[1]	89	100	272	319
Net occupancy expense	[1]	90	84	254	248
Leasing business expense	[1]	35	40	103	97
Equipment expense	[1]	33	33	97	96
Card and processing expense	[1]	29	33	89	98
Marketing expense	[1]	23	40	74	117
Other noninterest expense		225	245	682	681
Total noninterest expense	[1]	1,161	1,159	3,482	3,499
Income Before Income Taxes		746	689	1,051	2,261
Applicable income tax expense (benefit)		165	140	228	483
Net Income		581	549	823	1,778
Impairment losses on bank premises		11	5	25	27
Impairment charges of operating lease equipment				3
Bank premises and equipment held for sale		45	87	45	87	27
Impairment losses and termination charges		1	5	6	12
General Corporate and Other
Segment Reporting Information
Total goodwill		0	0	0	0
Total assets		13,564	(9,217)	13,564	(9,217)
Net interest income		257	(111)	321	(369)
Provision for (benefit from) credit losses		(422)	8	64	12
Net Interest Income After Provision for (Benefit from) Credit Losses		679	(119)	257	(381)
Noninterest Income:
Service charges on deposits		0	(1)	0	(2)
Wealth and asset management revenue		0	0	0	0
Commercial banking revenue		(1)	0	(3)	0
Mortgage banking net revenue		0	0	0	0
Card and processing revenue		3	3	10	3
Leasing business revenue		0	0	0	0
Other noninterest income		(7)	10	(37)	542
Securities gains, net		51	5	48	30
Securities losses, net – non-qualifying hedges on MSRs		0	0	0	0
Total noninterest income		46	17	18	573
Noninterest expense:
Compensation and benefits		237	219	688	742
Technology and communications		83	94	253	301
Net occupancy expense		33	27	84	79
Leasing business expense		0	0	0	0
Equipment expense		17	14	46	42
Card and processing expense		(1)	(1)	(3)	(1)
Marketing expense		14	18	41	56
Other noninterest expense		(324)	(312)	(988)	(919)
Total noninterest expense		59	59	121	300
Income Before Income Taxes		666	(161)	154	(108)
Applicable income tax expense (benefit)		158	(24)	71	21
Net Income		508	(137)	83	(129)
Bank premises and equipment held for sale		45	87	45	87
Eliminations
Segment Reporting Information
Total goodwill		0	0	0	0
Total assets		0	0	0	0
Net interest income		0	0	0	0
Provision for (benefit from) credit losses		0	0	0	0
Net Interest Income After Provision for (Benefit from) Credit Losses		0	0	0	0
Noninterest Income:
Service charges on deposits		0	0	0	0
Wealth and asset management revenue		(39)	(37)	(114)	(106)
Commercial banking revenue		0	0	0	0
Mortgage banking net revenue		0	0	0	0
Card and processing revenue		0	0	0	0
Leasing business revenue		0	0	0	0
Other noninterest income		0	0	0	0
Securities gains, net		0	0	0	0
Securities losses, net – non-qualifying hedges on MSRs		0	0	0	0
Total noninterest income		(39)	(37)	(114)	(106)
Noninterest expense:
Compensation and benefits		0	0	0	0
Technology and communications		0	0	0	0
Net occupancy expense		0	0	0	0
Leasing business expense		0	0	0	0
Equipment expense		0	0	0	0
Card and processing expense		0	0	0	0
Marketing expense		0	0	0	0
Other noninterest expense		(39)	(37)	(114)	(106)
Total noninterest expense		(39)	(37)	(114)	(106)
Income Before Income Taxes		0	0	0	0
Applicable income tax expense (benefit)		0	0	0	0
Net Income		0	0	0	0
Commercial Banking
Segment Reporting Information
Total goodwill		1,961		1,961		1,954	630
Commercial Banking | Operating Segments
Segment Reporting Information
Total goodwill		1,961	1,982	1,961	1,982
Total assets		72,025	75,143	72,025	75,143
Net interest income		432	623	1,512	1,761
Provision for (benefit from) credit losses		337	54	839	100
Net Interest Income After Provision for (Benefit from) Credit Losses		95	569	673	1,661
Noninterest Income:
Service charges on deposits		91	79	253	227
Wealth and asset management revenue		1	1	2	2
Commercial banking revenue		125	122	386	329
Mortgage banking net revenue		0	0	0	0
Card and processing revenue		13	16	40	49
Leasing business revenue		77	92	207	199
Other noninterest income		11	25	9	55
Securities gains, net		0	0	0	0
Securities losses, net – non-qualifying hedges on MSRs		0	0	0	0
Total noninterest income		318	335	897	861
Noninterest expense:
Compensation and benefits		127	118	405	346
Technology and communications		3	3	10	8
Net occupancy expense		8	7	23	21
Leasing business expense		35	40	103	97
Equipment expense		6	7	20	18
Card and processing expense		2	2	6	6
Marketing expense		2	3	5	6
Other noninterest expense		228	245	722	696
Total noninterest expense		411	425	1,294	1,198
Income Before Income Taxes		2	479	276	1,324
Applicable income tax expense (benefit)		(10)	86	27	242
Net Income		12	393	249	1,082
Branch Banking
Segment Reporting Information
Total goodwill		2,047		2,047		2,046	1,655
Branch Banking | Operating Segments
Segment Reporting Information
Total goodwill		2,047	2,054	2,047	2,054
Total assets		77,018	69,021	77,018	69,021
Net interest income		355	598	1,372	1,802
Provision for (benefit from) credit losses		68	58	182	164
Net Interest Income After Provision for (Benefit from) Credit Losses		287	540	1,190	1,638
Noninterest Income:
Service charges on deposits		53	65	160	191
Wealth and asset management revenue		44	41	128	117
Commercial banking revenue		1	1	3	3
Mortgage banking net revenue		2	2	6	4
Card and processing revenue		76	74	209	212
Leasing business revenue		0	0	0	0
Other noninterest income		16	21	49	63
Securities gains, net		0	0	0	0
Securities losses, net – non-qualifying hedges on MSRs		0	0	0	0
Total noninterest income		192	204	555	590
Noninterest expense:
Compensation and benefits		162	148	491	444
Technology and communications		1	1	2	3
Net occupancy expense		44	44	131	130
Leasing business expense		0	0	0	0
Equipment expense		10	12	31	35
Card and processing expense		28	32	86	92
Marketing expense		6	17	23	49
Other noninterest expense		209	215	635	622
Total noninterest expense		460	469	1,399	1,375
Income Before Income Taxes		19	275	346	853
Applicable income tax expense (benefit)		4	58	73	179
Net Income		15	217	273	674
Consumer Lending
Segment Reporting Information
Total goodwill		0		0		0	0
Consumer Lending | Operating Segments
Segment Reporting Information
Total goodwill		0	0	0	0
Total assets		27,869	26,171	27,869	26,171
Net interest income		98	88	279	234
Provision for (benefit from) credit losses		2	14	25	34
Net Interest Income After Provision for (Benefit from) Credit Losses		96	74	254	200
Noninterest Income:
Service charges on deposits		0	0	0	0
Wealth and asset management revenue		0	0	0	0
Commercial banking revenue		0	0	0	0
Mortgage banking net revenue		72	92	286	209
Card and processing revenue		0	0	0	0
Leasing business revenue		0	0	0	0
Other noninterest income		2	4	8	10
Securities gains, net		0	0	0	0
Securities losses, net – non-qualifying hedges on MSRs		(1)	0	3	5
Total noninterest income		73	96	297	224
Noninterest expense:
Compensation and benefits		57	48	162	146
Technology and communications		2	2	6	6
Net occupancy expense		2	3	7	8
Leasing business expense		0	0	0	0
Equipment expense		0	0	0	0
Card and processing expense		0	0	0	0
Marketing expense		1	1	3	3
Other noninterest expense		75	60	204	172
Total noninterest expense		137	114	382	335
Income Before Income Taxes		32	56	169	89
Applicable income tax expense (benefit)		7	12	35	19
Net Income		25	44	134	70
Wealth and Asset Management
Segment Reporting Information
Total goodwill		253		253		$ 252	$ 193
Wealth and Asset Management | Operating Segments
Segment Reporting Information
Total goodwill		253	254	253	254
Total assets		11,520	9,961	11,520	9,961
Net interest income		28	44	116	141
Provision for (benefit from) credit losses		0	0	0	0
Net Interest Income After Provision for (Benefit from) Credit Losses		28	44	116	141
Noninterest Income:
Service charges on deposits		0	0	1	1
Wealth and asset management revenue		126	119	371	345
Commercial banking revenue		0	0	1	1
Mortgage banking net revenue		2	1	3	1
Card and processing revenue		0	1	1	2
Leasing business revenue		0	0	0	0
Other noninterest income		4	4	13	9
Securities gains, net		0	0	0	0
Securities losses, net – non-qualifying hedges on MSRs		0	0	0	0
Total noninterest income		132	125	390	359
Noninterest expense:
Compensation and benefits		54	51	165	165
Technology and communications		0	0	1	1
Net occupancy expense		3	3	9	10
Leasing business expense		0	0	0	0
Equipment expense		0	0	0	1
Card and processing expense		0	0	0	1
Marketing expense		0	1	2	3
Other noninterest expense		76	74	223	216
Total noninterest expense		133	129	400	397
Income Before Income Taxes		27	40	106	103
Applicable income tax expense (benefit)		6	8	22	22
Net Income		$ 21	$ 32	$ 84	$ 81

[1] During the first quarter of 2020, certain noninterest income and noninterest expense line items were reclassified to better align disclosures to business activities. These reclassifications were retrospectively applied to all prior periods presented. Total noninterest income and noninterest expense did not change as a result of these reclassifications.