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
Mar. 31, 2026	Mar. 31, 2025
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified in period, amount	$ 362	$ 254
Commercial
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified, after 12 months	627	522
Financing receivable, excluding accrued interest, modified in period, amount	334	224
Commercial \| Commercial and industrial loans
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified, after 12 months	399	252
Financing receivable, excluding accrued interest, modified in period, amount	289	121
Commercial \| Commercial mortgage owner-occupied loans
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified, after 12 months	39	90
Financing receivable, excluding accrued interest, modified in period, amount	9	29
Commercial \| Commercial mortgage nonowner-occupied loans
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified, after 12 months	89	72
Financing receivable, excluding accrued interest, modified in period, amount	4	24
Commercial \| Commercial construction loans
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified, after 12 months	100	108
Financing receivable, excluding accrued interest, modified in period, amount	32	50
Commercial \| Current
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified, after 12 months	557	458
Commercial \| Current \| Commercial and industrial loans
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified, after 12 months	361	213
Commercial \| Current \| Commercial mortgage owner-occupied loans
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified, after 12 months	39	66
Commercial \| Current \| Commercial mortgage nonowner-occupied loans
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified, after 12 months	88	72
Commercial \| Current \| Commercial construction loans
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified, after 12 months	69	107
Commercial \| 30-89 days past due
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified, after 12 months	43	7
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	11	6
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
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	1	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	31	1
Commercial \| 90 Days or More
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified, after 12 months	27	57
Commercial \| 90 Days or More \| Commercial and industrial loans
Financing Receivable, Recorded Investment, Past Due
Financing receivable, excluding accrued interest, modified, after 12 months	27	33
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	24
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
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

Amortized cost excluding accrued interest, of financing receivable 12 months after modification for debtor experiencing financial difficulty.

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