Credit Quality and the Allowance for Loan and Lease Losses - Summary of Commercial Loans That Were Modified for Borrowers Experiencing Financial Difficulty (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	$ 737	$ 377	$ 1,100	$ 526
Commercial
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified, after 12 months	1,184	678	1,184	678
Financing receivable, excluding accrued interest, modified in period, amount	720	333	1,009	455
Commercial \| Commercial and industrial loans
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified, after 12 months	834	386	834	386
Financing receivable, excluding accrued interest, modified in period, amount	525	243	775	283
Commercial \| Commercial mortgage owner-occupied loans
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified, after 12 months	84	123	84	123
Financing receivable, excluding accrued interest, modified in period, amount	79	49	82	77
Commercial \| Commercial mortgage nonowner-occupied loans
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified, after 12 months	169	51	169	51
Financing receivable, excluding accrued interest, modified in period, amount	83	0	85	2
Commercial \| Commercial construction loans
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified, after 12 months	97	118	97	118
Financing receivable, excluding accrued interest, modified in period, amount	33	41	67	93
Commercial \| Current
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified, after 12 months	1,149	590	1,149	590
Commercial \| Current \| Commercial and industrial loans
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified, after 12 months	801	321	801	321
Commercial \| Current \| Commercial mortgage owner-occupied loans
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified, after 12 months	84	100	84	100
Commercial \| Current \| Commercial mortgage nonowner-occupied loans
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified, after 12 months	167	51	167	51
Commercial \| Current \| Commercial construction loans
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified, after 12 months	97	118	97	118
Commercial \| 30-89 days past due
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified, after 12 months	26	3	26	3
Commercial \| 30-89 days past due \| Commercial and industrial loans
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified, after 12 months	24	3	24	3
Commercial \| 30-89 days past due \| Commercial mortgage owner-occupied loans
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified, after 12 months	0	0	0	0
Commercial \| 30-89 days past due \| Commercial mortgage nonowner-occupied loans
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified, after 12 months	2	0	2	0
Commercial \| 30-89 days past due \| Commercial construction loans
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified, after 12 months	0	0	0	0
Commercial \| 90 Days or More
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified, after 12 months	9	85	9	85
Commercial \| 90 Days or More \| Commercial and industrial loans
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified, after 12 months	9	62	9	62
Commercial \| 90 Days or More \| Commercial mortgage owner-occupied loans
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified, after 12 months	0	23	0	23
Commercial \| 90 Days or More \| Commercial mortgage nonowner-occupied loans
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified, after 12 months	0	0	0	0
Commercial \| 90 Days or More \| Commercial construction loans
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified, after 12 months	$ 0	$ 0	$ 0	$ 0

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