Business Segments - Results of Operations and Average Assets by Segment (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information
Net interest income		$ 1,200	$ 1,245	$ 2,429	$ 2,327
Provision for credit losses		485	85	1,125	175
Net Interest Income After Provision for Credit Losses		715	1,160	1,304	2,152
Noninterest Income:
Service charges on deposits	[1]	122	143	270	274
Commercial banking revenue	[1]	137	107	261	209
Wealth and asset management revenue	[1]	120	122	255	234
Mortgage banking net revenue	[1]	99	63	219	119
Card and processing revenue	[1]	82	92	167	171
Leasing business revenue	[1]	57	76	131	108
Other noninterest income	[1]	12	47	18	616
Securities gains, net	[1]	21	8	(3)	25
Securities gains, net – non-qualifying hedges on MSRs	[1]	0	2	3	5
Total noninterest income	[1]	650	660	1,321	1,761
Noninterest expense:
Compensation and benefits	[1]	627	641	1,274	1,251
Technology and communications	[1]	90	136	183	219
Net occupancy expense	[1]	82	88	164	164
Leasing business expense	[1]	33	38	68	57
Equipment expense	[1]	32	33	64	63
Card and processing expense	[1]	29	34	60	64
Marketing expense	[1]	20	41	51	77
Other noninterest expense		208	232	457	446
Total noninterest expense	[1]	1,121	1,243	2,321	2,341
Income Before Income Taxes		244	577	304	1,572
Applicable income tax expense (benefit)		49	124	61	344
Net Income		195	453	243	1,228
Total goodwill		4,261	4,284	4,261	4,284	$ 4,252	$ 2,478
Total assets		202,906	168,802	202,906	168,802
Impairment losses on bank premises		12	2	14	22
Impairment charges of operating lease equipment				3
Bank premises and equipment held for sale		53	70	53	70	27
Impairment losses and termination charges		3	7	5	7
General Corporate and Other
Segment Reporting Information
Net interest income		(26)	(135)	65	(258)
Provision for credit losses		(33)	(2)	486	2
Net Interest Income After Provision for Credit Losses		7	(133)	(421)	(260)
Noninterest Income:
Service charges on deposits		1	(2)	0	(2)
Commercial banking revenue		(1)	1	(2)	0
Wealth and asset management revenue		0	0	0	0
Mortgage banking net revenue		0	0	0	0
Card and processing revenue		3	0	7	0
Leasing business revenue		0	0	0	0
Other noninterest income		(19)	1	(30)	532
Securities gains, net		21	8	(3)	25
Securities gains, net – non-qualifying hedges on MSRs		0	0	0	0
Total noninterest income		5	8	(28)	555
Noninterest expense:
Compensation and benefits		234	261	450	519
Technology and communications		84	130	171	207
Net occupancy expense		25	32	51	52
Leasing business expense		0	0	0	0
Equipment expense		15	15	29	27
Card and processing expense		(1)	0	(2)	(1)
Marketing expense		12	19	27	38
Other noninterest expense		(314)	(318)	(664)	(602)
Total noninterest expense		55	139	62	240
Income Before Income Taxes		(43)	(264)	(511)	55
Applicable income tax expense (benefit)		0	(41)	(88)	46
Net Income		(43)	(223)	(423)	9
Total goodwill		0	1,809	0	1,809
Total assets		11,119	(10,155)	11,119	(10,155)
Bank premises and equipment held for sale		53	70	53	70
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:
Service charges on deposits		0	0	0	0
Commercial banking revenue		0	0	0	0
Wealth and asset management revenue		(35)	(36)	(75)	(69)
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 gains, net – non-qualifying hedges on MSRs		0	0	0	0
Total noninterest income		(35)	(36)	(75)	(69)
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		(35)	(36)	(75)	(69)
Total noninterest expense		(35)	(36)	(75)	(69)
Income 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
Commercial Banking
Noninterest expense:
Total goodwill		1,961		1,961		1,954	630
Commercial Banking | Operating Segments
Segment Reporting Information
Net interest income		570	629	1,078	1,138
Provision for credit losses		457	25	502	46
Net Interest Income After Provision for Credit Losses		113	604	576	1,092
Noninterest Income:
Service charges on deposits		79	82	162	149
Commercial banking revenue		136	105	260	207
Wealth and asset management revenue		1	1	2	1
Mortgage banking net revenue		0	0	0	0
Card and processing revenue		11	18	26	32
Leasing business revenue		57	76	131	108
Other noninterest income		10	19	(1)	30
Securities gains, net		0	0	0	0
Securities gains, net – non-qualifying hedges on MSRs		0	0	0	0
Total noninterest income		294	301	580	527
Noninterest expense:
Compensation and benefits		129	119	278	227
Technology and communications		3	3	6	5
Net occupancy expense		8	7	15	14
Leasing business expense		33	38	68	57
Equipment expense		7	6	14	12
Card and processing expense		2	2	4	4
Marketing expense		2	2	4	3
Other noninterest expense		221	243	495	454
Total noninterest expense		405	420	884	776
Income Before Income Taxes		2	485	272	843
Applicable income tax expense (benefit)		(10)	90	35	156
Net Income		12	395	237	687
Total goodwill		1,961	630	1,961	630
Total assets		76,437	74,033	76,437	74,033
Branch Banking
Noninterest expense:
Total goodwill		2,047		2,047		2,046	1,655
Branch Banking | Operating Segments
Segment Reporting Information
Net interest income		513	620	1,017	1,204
Provision for credit losses		52	55	114	107
Net Interest Income After Provision for Credit Losses		461	565	903	1,097
Noninterest Income:
Service charges on deposits		42	63	107	127
Commercial banking revenue		1	1	2	2
Wealth and asset management revenue		39	40	84	76
Mortgage banking net revenue		2	1	4	2
Card and processing revenue		68	73	133	137
Leasing business revenue		0	0	0	0
Other noninterest income		15	24	34	42
Securities gains, net		0	0	0	0
Securities gains, net – non-qualifying hedges on MSRs		0	0	0	0
Total noninterest income		167	202	364	386
Noninterest expense:
Compensation and benefits		161	152	330	295
Technology and communications		1	1	1	2
Net occupancy expense		44	43	87	86
Leasing business expense		0	0	0	0
Equipment expense		10	12	21	24
Card and processing expense		28	32	58	61
Marketing expense		5	18	17	32
Other noninterest expense		205	209	426	407
Total noninterest expense		454	467	940	907
Income Before Income Taxes		174	300	327	576
Applicable income tax expense (benefit)		36	63	69	121
Net Income		138	237	258	455
Total goodwill		2,047	1,655	2,047	1,655
Total assets		77,219	69,577	77,219	69,577
Consumer Lending
Noninterest expense:
Total goodwill		0		0		0	0
Consumer Lending | Operating Segments
Segment Reporting Information
Net interest income		92	83	181	146
Provision for credit losses		10	7	23	20
Net Interest Income After Provision for Credit Losses		82	76	158	126
Noninterest Income:
Service charges on deposits		0	0	0	0
Commercial banking revenue		0	0	0	0
Wealth and asset management revenue		0	0	0	0
Mortgage banking net revenue		96	62	213	117
Card and processing revenue		0	0	0	0
Leasing business revenue		0	0	0	0
Other noninterest income		2	3	6	7
Securities gains, net		0	0	0	0
Securities gains, net – non-qualifying hedges on MSRs		0	2	3	5
Total noninterest income		98	67	222	129
Noninterest expense:
Compensation and benefits		53	52	104	97
Technology and communications		2	2	5	4
Net occupancy expense		2	3	5	5
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	2	2
Other noninterest expense		62	60	128	112
Total noninterest expense		120	118	244	220
Income Before Income Taxes		60	25	136	35
Applicable income tax expense (benefit)		12	5	29	7
Net Income		48	20	107	28
Total goodwill		0	0	0	0
Total assets		26,451	25,506	26,451	25,506
Wealth and Asset Management
Noninterest expense:
Total goodwill		253		253		$ 252	$ 193
Wealth and Asset Management | Operating Segments
Segment Reporting Information
Net interest income		51	48	88	97
Provision for credit losses		(1)	0	0	0
Net Interest Income After Provision for Credit Losses		52	48	88	97
Noninterest Income:
Service charges on deposits		0	0	1	0
Commercial banking revenue		1	0	1	0
Wealth and asset management revenue		115	117	244	226
Mortgage banking net revenue		1	0	2	0
Card and processing revenue		0	1	1	2
Leasing business revenue		0	0	0	0
Other noninterest income		4	0	9	5
Securities gains, net		0	0	0	0
Securities gains, net – non-qualifying hedges on MSRs		0	0	0	0
Total noninterest income		121	118	258	233
Noninterest expense:
Compensation and benefits		50	57	112	113
Technology and communications		0	0	0	1
Net occupancy expense		3	3	6	7
Leasing business expense		0	0	0	0
Equipment expense		0	0	0	0
Card and processing expense		0	0	0	0
Marketing expense		0	1	1	2
Other noninterest expense		69	74	147	144
Total noninterest expense		122	135	266	267
Income Before Income Taxes		51	31	80	63
Applicable income tax expense (benefit)		11	7	16	14
Net Income		40	24	64	49
Total goodwill		253	190	253	190
Total assets		$ 11,680	$ 9,841	$ 11,680	$ 9,841

[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.