Loans and Leases - Accruing And Non-Accruing Loans By Class (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current, Accruing	$ 54,989	$ 57,730
Total Accruing	55,088	57,847
Current, Non-Accruing	215	205
Total Non-Accruing	347	386
Loans and leases	55,435	58,232
30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, Accruing	83	100
Past Due, Non-Accruing	16	66
90+ Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, Accruing	16	17
Past Due, Non-Accruing	116	115
Commercial | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current, Accruing	31,335	32,945
Total Accruing	31,372	32,960
Current, Non-Accruing	119	88
Total Non-Accruing	144	144
Loans and leases	31,516	33,104
Commercial | Commercial and industrial | 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, Accruing	36	15
Past Due, Non-Accruing	9	12
Commercial | Commercial and industrial | 90+ Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, Accruing	1	0
Past Due, Non-Accruing	16	44
Commercial | Commercial and industrial | C&I
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current, Accruing	26,196	27,541
Total Accruing	26,233	27,556
Current, Non-Accruing	119	88
Total Non-Accruing	144	144
Nonaccrual, no allowance	129	101
Loans and leases	26,377	27,700
Commercial | Commercial and industrial | C&I | 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, Accruing	36	15
Past Due, Non-Accruing	9	12
Commercial | Commercial and industrial | C&I | 90+ Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, Accruing	1	0
Past Due, Non-Accruing	16	44
Commercial | Commercial and industrial | Loans to mortgage companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current, Accruing	5,139	5,404
Total Accruing	5,139	5,404
Current, Non-Accruing	0	0
Total Non-Accruing	0	0
Loans and leases	5,139	5,404
Commercial | Commercial and industrial | Loans to mortgage companies | 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, Accruing	0	0
Past Due, Non-Accruing	0	0
Commercial | Commercial and industrial | Loans to mortgage companies | 90+ Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, Accruing	0	0
Past Due, Non-Accruing	0	0
Commercial | Commercial and industrial | CRE
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual, no allowance	52
Commercial | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	12,194	12,275
Commercial | Commercial real estate | CRE
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current, Accruing		12,194
Total Accruing		12,217
Current, Non-Accruing		10
Total Non-Accruing		58
Loans and leases	12,194	12,275
Commercial | Commercial real estate | CRE | 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, Accruing		23
Past Due, Non-Accruing		42
Commercial | Commercial real estate | CRE | 90+ Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, Accruing		0
Past Due, Non-Accruing		6
Commercial real estate | Commercial real estate | CRE
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current, Accruing	12,120
Total Accruing	12,136
Current, Non-Accruing	8
Total Non-Accruing	58
Loans and leases	12,194
Commercial real estate | Commercial real estate | CRE | 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, Accruing	15
Past Due, Non-Accruing	0
Commercial real estate | Commercial real estate | CRE | 90+ Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, Accruing	1
Past Due, Non-Accruing	50
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]
Current, Accruing	10,604	11,474
Total Accruing	10,644	11,543
Current, Non-Accruing	88	106
Total Non-Accruing	143	182
Loans and leases	10,787	11,725
Consumer | Consumer Real Estate | 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, Accruing	28	53
Past Due, Non-Accruing	6	12
Consumer | Consumer Real Estate | 90+ Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, Accruing	12	16
Past Due, Non-Accruing	49	64
Consumer | Consumer Real Estate | HELOC
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current, Accruing	1,979	2,336
Total Accruing	1,991	2,360
Current, Non-Accruing	37	43
Total Non-Accruing	50	60
Nonaccrual, no allowance	7
Loans and leases	2,041	2,420
Consumer | Consumer Real Estate | HELOC | 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, Accruing	5	13
Past Due, Non-Accruing	2	3
Consumer | Consumer Real Estate | HELOC | 90+ Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, Accruing	7	11
Past Due, Non-Accruing	11	14
Consumer | Consumer Real Estate | Real estate installment loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current, Accruing	8,625	9,138
Total Accruing	8,653	9,183
Current, Non-Accruing	51	63
Total Non-Accruing	93	122
Nonaccrual, no allowance	52
Loans and leases	8,746	9,305
Consumer | Consumer Real Estate | Real estate installment loans | 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, Accruing	23	40
Past Due, Non-Accruing	4	9
Consumer | Consumer Real Estate | Real estate installment loans | 90+ Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, Accruing	5	5
Past Due, Non-Accruing	38	50
Consumer | Credit Card and Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current, Accruing	930	1,117
Total Accruing	936	1,127
Current, Non-Accruing	0	1
Total Non-Accruing	2	2
Loans and leases	938	1,128
Consumer | Credit Card and Other | 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, Accruing	4	9
Past Due, Non-Accruing	1	0
Consumer | Credit Card and Other | 90+ Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, Accruing	2	1
Past Due, Non-Accruing	1	1
Consumer | Credit Card and Other | Credit Card
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current, Accruing	274	279
Total Accruing	279	283
Current, Non-Accruing	0	0
Total Non-Accruing	0	0
Loans and leases	279	283
Consumer | Credit Card and Other | Credit Card | 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, Accruing	3	3
Past Due, Non-Accruing	0	0
Consumer | Credit Card and Other | Credit Card | 90+ Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, Accruing	2	1
Past Due, Non-Accruing	0	0
Consumer | Credit Card and Other | Other Consumer Loans Class
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current, Accruing	656	838
Total Accruing	657	844
Current, Non-Accruing	0	1
Total Non-Accruing	2	2
Loans and leases	659	845
Consumer | Credit Card and Other | Other Consumer Loans Class | 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, Accruing	1	6
Past Due, Non-Accruing	1	0
Consumer | Credit Card and Other | Other Consumer Loans Class | 90+ Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due, Accruing	0	0
Past Due, Non-Accruing	$ 1	$ 1