Loans and Leases - Loans by FICO Score (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 55,435	$ 58,232
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	10,787	11,725
Consumer | Consumer real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, originated year one	1,610	1,747
Financing receivable, originated year two	1,559	1,670
Financing receivable, originated year three	1,215	1,093
Financing receivable, originated year four	794	920
Financing receivable, originated year five	1,312	1,054
Financing receivable, originated prior to year five	2,256	2,821
Revolving loans	1,748	2,055
Revolving Loans converted to term loans	293	365
Loans and leases	10,787	11,725
Consumer | Consumer real estate | FICO score 740 or greater
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, originated year one	1,037	1,186
Financing receivable, originated year two	1,085	1,167
Financing receivable, originated year three	844	703
Financing receivable, originated year four	500	610
Financing receivable, originated year five	682	674
Financing receivable, originated prior to year five	1,692	1,719
Revolving loans	1,104	1,275
Revolving Loans converted to term loans	130	159
Loans and leases	7,074	7,493
Consumer | Consumer real estate | FICO score 720-739
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, originated year one	135	157
Financing receivable, originated year two	143	158
Financing receivable, originated year three	111	100
Financing receivable, originated year four	78	77
Financing receivable, originated year five	107	92
Financing receivable, originated prior to year five	119	197
Revolving loans	164	186
Revolving Loans converted to term loans	24	29
Loans and leases	881	996
Consumer | Consumer real estate | FICO score 700-719
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, originated year one	98	122
Financing receivable, originated year two	109	107
Financing receivable, originated year three	78	78
Financing receivable, originated year four	55	76
Financing receivable, originated year five	117	73
Financing receivable, originated prior to year five	131	221
Revolving loans	146	177
Revolving Loans converted to term loans	25	34
Loans and leases	759	888
Consumer | Consumer real estate | FICO score 660-699
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, originated year one	99	130
Financing receivable, originated year two	137	141
Financing receivable, originated year three	101	123
Financing receivable, originated year four	97	75
Financing receivable, originated year five	148	85
Financing receivable, originated prior to year five	147	296
Revolving loans	215	264
Revolving Loans converted to term loans	48	59
Loans and leases	992	1,173
Consumer | Consumer real estate | FICO score 620-659
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, originated year one	15	45
Financing receivable, originated year two	33	61
Financing receivable, originated year three	51	37
Financing receivable, originated year four	23	28
Financing receivable, originated year five	65	35
Financing receivable, originated prior to year five	67	127
Revolving loans	71	92
Revolving Loans converted to term loans	31	36
Loans and leases	356	461
Consumer | Consumer real estate | FICO score less than 620
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, originated year one	226	107
Financing receivable, originated year two	52	36
Financing receivable, originated year three	30	52
Financing receivable, originated year four	41	54
Financing receivable, originated year five	193	95
Financing receivable, originated prior to year five	100	261
Revolving loans	48	61
Revolving Loans converted to term loans	35	48
Loans and leases	725	714
Consumer | Credit Card and Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, originated year one	107	122
Financing receivable, originated year two	65	91
Financing receivable, originated year three	55	107
Financing receivable, originated year four	52	78
Financing receivable, originated year five	39	63
Financing receivable, originated prior to year five	184	279
Revolving loans	423	373
Revolving Loans converted to term loans	13	15
Loans and leases	938	1,128
Consumer | Credit Card and Other | FICO score 740 or greater
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, originated year one	55	57
Financing receivable, originated year two	38	52
Financing receivable, originated year three	33	59
Financing receivable, originated year four	27	37
Financing receivable, originated year five	18	23
Financing receivable, originated prior to year five	70	116
Revolving loans	212	159
Revolving Loans converted to term loans	5	5
Loans and leases	458	508
Consumer | Credit Card and Other | FICO score 720-739
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, originated year one	9	7
Financing receivable, originated year two	6	7
Financing receivable, originated year three	5	9
Financing receivable, originated year four	4	8
Financing receivable, originated year five	4	8
Financing receivable, originated prior to year five	20	27
Revolving loans	39	91
Revolving Loans converted to term loans	2	2
Loans and leases	89	159
Consumer | Credit Card and Other | FICO score 700-719
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, originated year one	6	9
Financing receivable, originated year two	6	8
Financing receivable, originated year three	5	9
Financing receivable, originated year four	5	8
Financing receivable, originated year five	4	4
Financing receivable, originated prior to year five	24	38
Revolving loans	42	37
Revolving Loans converted to term loans	1	3
Loans and leases	93	116
Consumer | Credit Card and Other | FICO score 660-699
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, originated year one	22	30
Financing receivable, originated year two	7	12
Financing receivable, originated year three	6	15
Financing receivable, originated year four	7	9
Financing receivable, originated year five	6	9
Financing receivable, originated prior to year five	33	48
Revolving loans	93	46
Revolving Loans converted to term loans	2	3
Loans and leases	176	172
Consumer | Credit Card and Other | FICO score 620-659
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, originated year one	3	5
Financing receivable, originated year two	3	5
Financing receivable, originated year three	3	7
Financing receivable, originated year four	4	5
Financing receivable, originated year five	3	10
Financing receivable, originated prior to year five	19	24
Revolving loans	21	20
Revolving Loans converted to term loans	1	1
Loans and leases	57	77
Consumer | Credit Card and Other | FICO score less than 620
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, originated year one	12	14
Financing receivable, originated year two	5	7
Financing receivable, originated year three	3	8
Financing receivable, originated year four	5	11
Financing receivable, originated year five	4	9
Financing receivable, originated prior to year five	18	26
Revolving loans	16	20
Revolving Loans converted to term loans	2	1
Loans and leases	65	96
HELOC | Consumer | Consumer real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	2,041	$ 2,420
Revolving loans converted to term loan during period	34
Credit Card And Other, Other Consumer Loans | Consumer | Credit Card and Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revolving loans converted to term loan during period	$ 4