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, 2023	Dec. 31, 2022
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases	[1],[2]	$ 120,088	$ 121,480
Commercial
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		75,118	76,389
90 Days Past Due and Still Accruing		3	13
Commercial | Current
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		74,991	76,211
Commercial | Total Past Due
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		127	178
Commercial | 30 to 89 Days
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		79	129
Commercial | 90 Days or More
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		48	49
Commercial | Commercial and industrial loans
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		55,790	57,232
90 Days Past Due and Still Accruing		3	11
Commercial | Commercial and industrial loans | Current
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		55,697	57,092
Commercial | Commercial and industrial loans | Total Past Due
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		93	140
Commercial | Commercial and industrial loans | 30 to 89 Days
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		48	98
Commercial | Commercial and industrial loans | 90 Days or More
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		45	42
Commercial | Commercial mortgage owner-occupied loans
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		5,351	5,258
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		5,346	5,241
Commercial | Commercial mortgage owner-occupied loans | Total Past Due
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		5	17
Commercial | Commercial mortgage owner-occupied loans | 30 to 89 Days
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		2	14
Commercial | Commercial mortgage owner-occupied loans | 90 Days or More
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		3	3
Commercial | Commercial mortgage nonowner-occupied loans
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		5,771	5,762
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		5,771	5,756
Commercial | Commercial mortgage nonowner-occupied loans | Total Past Due
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		0	6
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		0	0
Commercial | Commercial construction loans
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		5,582	5,433
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		5,576	5,424
Commercial | Commercial construction loans | Total Past Due
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		6	9
Commercial | Commercial construction loans | 30 to 89 Days
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		6	7
Commercial | Commercial construction loans | 90 Days or More
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		0	2
Commercial | Commercial leases
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		2,624	2,704
90 Days Past Due and Still Accruing		0	2
Commercial | Commercial leases | Current
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		2,601	2,698
Commercial | Commercial leases | Total Past Due
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		23	6
Commercial | Commercial leases | 30 to 89 Days
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		23	4
Commercial | Commercial leases | 90 Days or More
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		$ 0	$ 2

[1] Includes $113 and $123 of residential mortgage loans measured at fair value at September 30, 2023 and December 31, 2022, respectively.

[2] Includes $59 and $17 of other short-term investments, $1,728 and $185 of portfolio loans and leases, $(27) and $(2) of ALLL, $11 and $2 of other assets, $15 and $9 of other liabilities, and $1,553 and $118 of long-term debt from consolidated VIEs that are included in their respective captions above at September 30, 2023 and December 31, 2022, respectively. For further information, refer to Note 12.