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		Jun. 30, 2024	Dec. 31, 2023
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases	[1]	$ 116,579	$ 117,234
Commercial
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		71,783	72,746
90 Days Past Due and Still Accruing		8	8
Commercial | Current
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		71,612	72,547
Commercial | Total Past Due
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		171	199
Commercial | 30 to 89 Days
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		77	93
Commercial | 90 Days or More
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		94	106
Commercial | Commercial and industrial loans
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		51,840	53,270
90 Days Past Due and Still Accruing		3	8
Commercial | Commercial and industrial loans | Current
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		51,724	53,107
Commercial | Commercial and industrial loans | Total Past Due
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		116	163
Commercial | Commercial and industrial loans | 30 to 89 Days
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		28	61
Commercial | Commercial and industrial loans | 90 Days or More
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		88	102
Commercial | Commercial mortgage owner-occupied loans
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		5,416	5,200
90 Days Past Due and Still Accruing		1	0
Commercial | Commercial mortgage owner-occupied loans | Current
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		5,411	5,196
Commercial | Commercial mortgage owner-occupied loans | Total Past Due
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		5	4
Commercial | Commercial mortgage owner-occupied loans | 30 to 89 Days
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		3	1
Commercial | Commercial mortgage owner-occupied loans | 90 Days or More
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		2	3
Commercial | Commercial mortgage nonowner-occupied loans
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		6,013	6,076
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		6,010	6,061
Commercial | Commercial mortgage nonowner-occupied loans | Total Past Due
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		3	15
Commercial | Commercial mortgage nonowner-occupied loans | 30 to 89 Days
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		3	14
Commercial | Commercial mortgage nonowner-occupied loans | 90 Days or More
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		0	1
Commercial | Commercial construction loans
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		5,806	5,621
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		5,781	5,621
Commercial | Commercial construction loans | Total Past Due
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		25	0
Commercial | Commercial construction loans | 30 to 89 Days
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		25	0
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		2,708	2,579
90 Days Past Due and Still Accruing		4	0
Commercial | Commercial leases | Current
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		2,686	2,562
Commercial | Commercial leases | Total Past Due
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		22	17
Commercial | Commercial leases | 30 to 89 Days
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		18	17
Commercial | Commercial leases | 90 Days or More
Financing Receivable, Recorded Investment, Past Due
Total portfolio loans and leases		$ 4	$ 0

[1] Includes $52 and $55 of other short-term investments, $1,272 and $1,573 of portfolio loans and leases, $(23) and $(28) of ALLL, $7 and $10 of other assets, $13 and $14 of other liabilities and $1,136 and $1,409 of long-term debt from consolidated VIEs that are included in their respective captions above at June 30, 2024 and December 31, 2023, respectively. For further information, refer to Note 11.