Loans and Leases - Balances of Commercial Loan Portfolio Classes, Disaggregated by PD Grade (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 63,058	$ 62,565
Commercial: | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, originated year one	2,776	5,780
Financing receivable, originated year two	5,619	2,818
Financing receivable, originated year three	2,385	3,840
Financing receivable, originated year four	3,358	2,562
Financing receivable, originated year five	2,083	1,121
Financing receivable, originated prior to year five	4,540	4,079
LMC	3,926	3,471
Revolving Loans	9,481	9,446
Revolving Loans Converted to Term Loans	233	311
Loans and leases	34,401	33,428
Commercial: | Commercial and industrial | Pass (PD grades 1 through 12)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, originated year one	2,749	5,590
Financing receivable, originated year two	5,395	2,607
Financing receivable, originated year three	2,218	3,649
Financing receivable, originated year four	3,066	2,336
Financing receivable, originated year five	1,892	1,055
Financing receivable, originated prior to year five	4,240	3,853
LMC	3,925	3,471
Revolving Loans	9,023	8,784
Revolving Loans Converted to Term Loans	199	248
Loans and leases	32,707	31,593
Commercial: | Commercial and industrial | Special Mention (PD grade 13)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, originated year one	4	106
Financing receivable, originated year two	80	27
Financing receivable, originated year three	7	78
Financing receivable, originated year four	52	47
Financing receivable, originated year five	30	33
Financing receivable, originated prior to year five	59	57
LMC	0	0
Revolving Loans	120	279
Revolving Loans Converted to Term Loans	6	2
Loans and leases	358	629
Commercial: | Commercial and industrial | Substandard, Doubtful, or Loss (PD grades 14,15, and 16)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, originated year one	23	84
Financing receivable, originated year two	144	184
Financing receivable, originated year three	160	113
Financing receivable, originated year four	240	179
Financing receivable, originated year five	161	33
Financing receivable, originated prior to year five	241	169
LMC	1	0
Revolving Loans	338	383
Revolving Loans Converted to Term Loans	28	61
Loans and leases	1,336	1,206
Commercial: | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	13,675	14,421
Commercial: | Commercial real estate | Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, originated year one	728	697
Financing receivable, originated year two	969	1,369
Financing receivable, originated year three	1,716	3,813
Financing receivable, originated year four	3,248	3,254
Financing receivable, originated year five	2,458	1,047
Financing receivable, originated prior to year five	4,100	3,847
Revolving Loans	369	346
Revolving Loans Converted to Term Loans	87	48
Loans and leases	13,675	14,421
Commercial: | Commercial real estate | Pass (PD grades 1 through 12) | Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, originated year one	723	694
Financing receivable, originated year two	954	1,296
Financing receivable, originated year three	1,686	3,282
Financing receivable, originated year four	2,583	2,778
Financing receivable, originated year five	2,097	894
Financing receivable, originated prior to year five	3,669	3,281
Revolving Loans	286	340
Revolving Loans Converted to Term Loans	87	47
Loans and leases	12,085	12,612
Commercial: | Commercial real estate | Special Mention (PD grade 13) | Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, originated year one	0	0
Financing receivable, originated year two	11	42
Financing receivable, originated year three	1	280
Financing receivable, originated year four	252	198
Financing receivable, originated year five	177	37
Financing receivable, originated prior to year five	60	130
Revolving Loans	34	0
Revolving Loans Converted to Term Loans	0	1
Loans and leases	535	688
Commercial: | Commercial real estate | Substandard, Doubtful, or Loss (PD grades 14,15, and 16) | Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, originated year one	5	3
Financing receivable, originated year two	4	31
Financing receivable, originated year three	29	251
Financing receivable, originated year four	413	278
Financing receivable, originated year five	184	116
Financing receivable, originated prior to year five	371	436
Revolving Loans	49	6
Revolving Loans Converted to Term Loans	0	0
Loans and leases	$ 1,055	$ 1,121