Credit Quality and the Allowance for Loan and Lease Losses - Summary of Recorded Investment in Portfolio Loans and Leases by Age and Class (Details) - USD ($) $ in Millions		Sep. 30, 2025	Dec. 31, 2024
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases	[1]	$ 123,130	$ 119,791
Commercial
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		74,423	73,293
90 Days Past Due and Still Accruing		2	6
Commercial | Current
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		74,120	73,047
Commercial | Total Past Due
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		303	246
Commercial | 30 to 89 Days
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		169	155
Commercial | 90 Days or More
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		134	91
Commercial | Commercial and industrial loans
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		53,947	52,271
90 Days Past Due and Still Accruing		2	5
Commercial | Commercial and industrial loans | Current
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		53,738	52,098
Commercial | Commercial and industrial loans | Total Past Due
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		209	173
Commercial | Commercial and industrial loans | 30 to 89 Days
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		91	90
Commercial | Commercial and industrial loans | 90 Days or More
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		118	83
Commercial | Commercial mortgage owner-occupied loans
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		6,039	6,023
90 Days Past Due and Still Accruing		0	0
Commercial | Commercial mortgage owner-occupied loans | Current
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		6,009	5,980
Commercial | Commercial mortgage owner-occupied loans | Total Past Due
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		30	43
Commercial | Commercial mortgage owner-occupied loans | 30 to 89 Days
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		19	40
Commercial | Commercial mortgage owner-occupied loans | 90 Days or More
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		11	3
Commercial | Commercial mortgage nonowner-occupied loans
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		5,893	6,223
90 Days Past Due and Still Accruing		0	0
Commercial | Commercial mortgage nonowner-occupied loans | Current
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		5,888	6,215
Commercial | Commercial mortgage nonowner-occupied loans | Total Past Due
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		5	8
Commercial | Commercial mortgage nonowner-occupied loans | 30 to 89 Days
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		0	6
Commercial | Commercial mortgage nonowner-occupied loans | 90 Days or More
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		5	2
Commercial | Commercial construction loans
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		5,326	5,588
90 Days Past Due and Still Accruing		0	0
Commercial | Commercial construction loans | Current
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		5,282	5,587
Commercial | Commercial construction loans | Total Past Due
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		44	1
Commercial | Commercial construction loans | 30 to 89 Days
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		44	1
Commercial | Commercial construction loans | 90 Days or More
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		0	0
Commercial | Commercial leases
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		3,218	3,188
90 Days Past Due and Still Accruing		0	1
Commercial | Commercial leases | Current
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		3,203	3,167
Commercial | Commercial leases | Total Past Due
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		15	21
Commercial | Commercial leases | 30 to 89 Days
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		15	18
Commercial | Commercial leases | 90 Days or More
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		$ 0	$ 3

[1] Includes $42 and $51 of other short-term investments, $649 and $1,000 of portfolio loans and leases, $(11) and $(19) of ALLL, $4 and $5 of other assets, $11 and $12 of other liabilities and $563 and $889 of long-term debt from consolidated VIEs that are included in their respective captions above at September 30, 2025 and December 31, 2024, respectively. For further information, refer to Note 7.