Asset Quality - Aging Analysis of Past Due and Current Loans (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Financing Receivable, Past Due [Line Items]
Total	$ 116,191	$ 101,854
Accrued interest	274	198
Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	79,597	70,836
Accrued interest	197	113
Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	36,594	31,018
Accrued interest	77	85
Non-performing Loans
Financing Receivable, Past Due [Line Items]
Total	390	454
Non-performing Loans | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	205	239
Non-performing Loans | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	185	215
Current
Financing Receivable, Past Due [Line Items]
Total	115,567	101,167
Current | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	79,232	70,439
Current | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	36,335	30,728
30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	138	76
30-59 Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	95	35
30-59 Days Past Due | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	43	41
60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	49	89
60-89 Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	33	75
60-89 Days Past Due | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	16	14
90 and Greater Days Past Due
Financing Receivable, Past Due [Line Items]
Total	47	68
90 and Greater Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	32	48
90 and Greater Days Past Due | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	15	20
Total Past Due and Non-performing Loans
Financing Receivable, Past Due [Line Items]
Total	624	687
Total Past Due and Non-performing Loans | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	365	397
Total Past Due and Non-performing Loans | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	259	290
Total commercial real estate loans | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	18,749	16,240
Total commercial real estate loans | Non-performing Loans | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	34	44
Total commercial real estate loans | Current | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	18,701	16,152
Total commercial real estate loans | 30-59 Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	4	10
Total commercial real estate loans | 60-89 Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	1	26
Total commercial real estate loans | 90 and Greater Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	9	8
Total commercial real estate loans | Total Past Due and Non-performing Loans | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	48	88
Commercial and Industrial | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	56,971	50,525
Commercial and Industrial | Non-performing Loans | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	169	191
Commercial and Industrial | Current | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	56,674	50,226
Commercial and Industrial | 30-59 Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	75	19
Commercial and Industrial | 60-89 Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	31	49
Commercial and Industrial | 90 and Greater Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	22	40
Commercial and Industrial | Total Past Due and Non-performing Loans | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	297	299
Commercial mortgage | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	16,400	14,244
Commercial mortgage | Non-performing Loans | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	34	44
Commercial mortgage | Current | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	16,353	14,174
Commercial mortgage | 30-59 Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	4	10
Commercial mortgage | 60-89 Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	1	9
Commercial mortgage | 90 and Greater Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	8	7
Commercial mortgage | Total Past Due and Non-performing Loans | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	47	70
Construction | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	2,349	1,996
Construction | Non-performing Loans | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	0	0
Construction | Current | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	2,348	1,978
Construction | 30-59 Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	0	0
Construction | 60-89 Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	0	17
Construction | 90 and Greater Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	1	1
Construction | Total Past Due and Non-performing Loans | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	1	18
Commercial lease financing | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	3,877	4,071
Commercial lease financing | Non-performing Loans | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	2	4
Commercial lease financing | Current | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	3,857	4,061
Commercial lease financing | 30-59 Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	16	6
Commercial lease financing | 60-89 Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	1	0
Commercial lease financing | 90 and Greater Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	1	0
Commercial lease financing | Total Past Due and Non-performing Loans | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	20	10
Real estate — residential mortgage | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	20,838	15,756
Real estate — residential mortgage | Non-performing Loans | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	66	72
Real estate — residential mortgage | Current | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	20,759	15,669
Real estate — residential mortgage | 30-59 Days Past Due | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	9	7
Real estate — residential mortgage | 60-89 Days Past Due | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	3	3
Real estate — residential mortgage | 90 and Greater Days Past Due | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	1	5
Real estate — residential mortgage | Total Past Due and Non-performing Loans | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	79	87
Home equity loans | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	7,926	8,467
Home equity loans | Non-performing Loans | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	112	135
Home equity loans | Current | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	7,787	8,299
Home equity loans | 30-59 Days Past Due | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	19	21
Home equity loans | 60-89 Days Past Due | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	4	6
Home equity loans | 90 and Greater Days Past Due | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	4	6
Home equity loans | Total Past Due and Non-performing Loans | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	139	168
Consumer direct loans | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	6,803	5,753
Consumer direct loans | Non-performing Loans | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	3	4
Consumer direct loans | Current | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	6,779	5,736
Consumer direct loans | 30-59 Days Past Due | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	11	8
Consumer direct loans | 60-89 Days Past Due | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	6	2
Consumer direct loans | 90 and Greater Days Past Due | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	4	3
Consumer direct loans | Total Past Due and Non-performing Loans | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	24	17
Credit cards | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total	166	139
Credit cards | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	977	972
Credit cards | Non-performing Loans | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	3	3
Credit cards | Current | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	961	956
Credit cards | 30-59 Days Past Due | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	4	4
Credit cards | 60-89 Days Past Due | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	3	3
Credit cards | 90 and Greater Days Past Due | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	6	6
Credit cards | Total Past Due and Non-performing Loans | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	16	16
Consumer indirect loans | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	50	70
Consumer indirect loans | Non-performing Loans | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	1	1
Consumer indirect loans | Current | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	49	68
Consumer indirect loans | 30-59 Days Past Due | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	0	1
Consumer indirect loans | 60-89 Days Past Due | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	0	0
Consumer indirect loans | 90 and Greater Days Past Due | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	0	0
Consumer indirect loans | Total Past Due and Non-performing Loans | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total	$ 1	$ 2