Asset Quality - Schedule of Aging Analysis of Past Due and Current Loans (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Financing Receivable, Past Due [Line Items]
Total loans	$ 105,902	$ 104,260
Accrued interest	472	456
Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	75,319	71,891
Accrued interest	351	322
Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans	30,583	32,369
Accrued interest	121	134
Non-performing Loans
Financing Receivable, Past Due [Line Items]
Total loans	658	758
Non-performing Loans | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	467	565
Non-performing Loans | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans	191	193
Current
Financing Receivable, Past Due [Line Items]
Total loans	104,880	103,206
Current | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	74,587	71,151
Current | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans	30,293	32,055
30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans	176	120
30-59 Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	125	53
30-59 Days Past Due | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans	51	67
60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans	78	86
60-89 Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	54	56
60-89 Days Past Due | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans	24	30
90 and Greater Days Past Due
Financing Receivable, Past Due [Line Items]
Total loans	110	90
90 and Greater Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	86	66
90 and Greater Days Past Due | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans	24	24
Total Past Due and Non-performing Loans
Financing Receivable, Past Due [Line Items]
Total loans	1,022	1,054
Total Past Due and Non-performing Loans | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	732	740
Total Past Due and Non-performing Loans | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans	290	314
Commercial and industrial | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	56,791	52,909
Commercial and industrial | Non-performing Loans | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	253	322
Commercial and industrial | Current | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	56,431	52,473
Commercial and industrial | 30-59 Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	45	48
Commercial and industrial | 60-89 Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	24	21
Commercial and industrial | 90 and Greater Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	38	45
Commercial and industrial | Total Past Due and Non-performing Loans | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	360	436
Total commercial real estate loans | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	16,195	16,246
Total commercial real estate loans | Non-performing Loans | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	214	243
Total commercial real estate loans | Current | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	15,824	15,950
Total commercial real estate loans | 30-59 Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	79	4
Total commercial real estate loans | 60-89 Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	30	29
Total commercial real estate loans | 90 and Greater Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	48	20
Total commercial real estate loans | Total Past Due and Non-performing Loans | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	371	296
Commercial mortgage | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	13,378	13,310
Commercial mortgage | Non-performing Loans | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	214	243
Commercial mortgage | Current | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	13,030	13,018
Commercial mortgage | Current | Total commercial loans | Government National Mortgage Association (GNMA)
Financing Receivable, Past Due [Line Items]
Total loans	69	75
Commercial mortgage | 30-59 Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	79	4
Commercial mortgage | 60-89 Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	8	29
Commercial mortgage | 90 and Greater Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	47	16
Commercial mortgage | Total Past Due and Non-performing Loans | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	348	292
Construction | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	2,817	2,936
Construction | Non-performing Loans | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	0	0
Construction | Current | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	2,794	2,932
Construction | 30-59 Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	0	0
Construction | 60-89 Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	22	0
Construction | 90 and Greater Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	1	4
Construction | Total Past Due and Non-performing Loans | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	23	4
Commercial lease financing | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	2,333	2,736
Commercial lease financing | Non-performing Loans | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	0	0
Commercial lease financing | Current | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	2,332	2,728
Commercial lease financing | 30-59 Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	1	1
Commercial lease financing | 60-89 Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	0	6
Commercial lease financing | 90 and Greater Days Past Due | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	0	1
Commercial lease financing | Total Past Due and Non-performing Loans | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	1	8
Real estate — residential mortgage | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans	19,008	19,886
Real estate — residential mortgage | Non-performing Loans | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans	98	92
Real estate — residential mortgage | Current | Total commercial loans | Government National Mortgage Association (GNMA)
Financing Receivable, Past Due [Line Items]
Total loans	5	7
Real estate — residential mortgage | Current | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans	18,891	19,766
Real estate — residential mortgage | 30-59 Days Past Due | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans	13	20
Real estate — residential mortgage | 60-89 Days Past Due | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans	6	8
Real estate — residential mortgage | 90 and Greater Days Past Due | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans	0	0
Real estate — residential mortgage | Total Past Due and Non-performing Loans | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans	117	120
Home equity loans | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans	5,863	6,358
Home equity loans | Non-performing Loans | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans	82	89
Home equity loans | Current | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans	5,754	6,232
Home equity loans | 30-59 Days Past Due | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans	18	26
Home equity loans | 60-89 Days Past Due | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans	5	8
Home equity loans | 90 and Greater Days Past Due | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans	4	3
Home equity loans | Total Past Due and Non-performing Loans | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans	109	126
Other consumer loans | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans	4,779	5,167
Other consumer loans | Non-performing Loans | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans	4	5
Other consumer loans | Current | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans	4,741	5,129
Other consumer loans | 30-59 Days Past Due | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans	15	15
Other consumer loans | 60-89 Days Past Due | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans	9	9
Other consumer loans | 90 and Greater Days Past Due | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans	10	9
Other consumer loans | Total Past Due and Non-performing Loans | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans	38	38
Credit cards | Total commercial loans
Financing Receivable, Past Due [Line Items]
Total loans	212	212
Credit cards | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans	933	958
Credit cards | Non-performing Loans | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans	7	7
Credit cards | Current | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans	907	928
Credit cards | 30-59 Days Past Due | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans	5	6
Credit cards | 60-89 Days Past Due | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans	4	5
Credit cards | 90 and Greater Days Past Due | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans	10	12
Credit cards | Total Past Due and Non-performing Loans | Total consumer loans
Financing Receivable, Past Due [Line Items]
Total loans	$ 26	$ 30