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	Mar. 31, 2022	Dec. 31, 2021
Financing Receivable, Recorded Investment, Past Due
Loans and Leases	$ 113,957	$ 110,158
Commercial
Financing Receivable, Recorded Investment, Past Due
Loans and Leases	72,938	70,268
90 Days Past Due and Still Accruing	11	19
Commercial | Current
Financing Receivable, Recorded Investment, Past Due
Loans and Leases	72,783	70,132
Commercial | Total Past Due
Financing Receivable, Recorded Investment, Past Due
Loans and Leases	155	136
Commercial | 30 to 89 Days
Financing Receivable, Recorded Investment, Past Due
Loans and Leases	112	81
Commercial | 90 Days or More
Financing Receivable, Recorded Investment, Past Due
Loans and Leases	43	55
Commercial | Commercial and industrial loans
Financing Receivable, Recorded Investment, Past Due
Loans and Leases	53,909	51,659
90 Days Past Due and Still Accruing	9	17
Loans and leases related to SBA Paycheck Protection Program of CARES Act	737	1,300
Commercial | Commercial and industrial loans | Current
Financing Receivable, Recorded Investment, Past Due
Loans and Leases	53,789	51,549
Commercial | Commercial and industrial loans | Total Past Due
Financing Receivable, Recorded Investment, Past Due
Loans and Leases	120	110
Commercial | Commercial and industrial loans | 30 to 89 Days
Financing Receivable, Recorded Investment, Past Due
Loans and Leases	86	61
Loans and leases related to SBA Paycheck Protection Program of CARES Act	5	20
Commercial | Commercial and industrial loans | 90 Days or More
Financing Receivable, Recorded Investment, Past Due
Loans and Leases	34	49
Loans and leases related to SBA Paycheck Protection Program of CARES Act	2	6
Commercial | Commercial mortgage owner-occupied loans
Financing Receivable, Recorded Investment, Past Due
Loans and Leases	4,976	4,709
90 Days Past Due and Still Accruing	1	1
Commercial | Commercial mortgage owner-occupied loans | Current
Financing Receivable, Recorded Investment, Past Due
Loans and Leases	4,968	4,701
Commercial | Commercial mortgage owner-occupied loans | Total Past Due
Financing Receivable, Recorded Investment, Past Due
Loans and Leases	8	8
Commercial | Commercial mortgage owner-occupied loans | 30 to 89 Days
Financing Receivable, Recorded Investment, Past Due
Loans and Leases	5	4
Commercial | Commercial mortgage owner-occupied loans | 90 Days or More
Financing Receivable, Recorded Investment, Past Due
Loans and Leases	3	4
Commercial | Commercial mortgage nonowner-occupied loans
Financing Receivable, Recorded Investment, Past Due
Loans and Leases	5,718	5,607
90 Days Past Due and Still Accruing	1	0
Commercial | Commercial mortgage nonowner-occupied loans | Current
Financing Receivable, Recorded Investment, Past Due
Loans and Leases	5,710	5,606
Commercial | Commercial mortgage nonowner-occupied loans | Total Past Due
Financing Receivable, Recorded Investment, Past Due
Loans and Leases	8	1
Commercial | Commercial mortgage nonowner-occupied loans | 30 to 89 Days
Financing Receivable, Recorded Investment, Past Due
Loans and Leases	5	0
Commercial | Commercial mortgage nonowner-occupied loans | 90 Days or More
Financing Receivable, Recorded Investment, Past Due
Loans and Leases	3	1
Commercial | Commercial construction loans
Financing Receivable, Recorded Investment, Past Due
Loans and Leases	5,420	5,241
90 Days Past Due and Still Accruing	0	1
Commercial | Commercial construction loans | Current
Financing Receivable, Recorded Investment, Past Due
Loans and Leases	5,411	5,241
Commercial | Commercial construction loans | Total Past Due
Financing Receivable, Recorded Investment, Past Due
Loans and Leases	9	0
Commercial | Commercial construction loans | 30 to 89 Days
Financing Receivable, Recorded Investment, Past Due
Loans and Leases	9	0
Commercial | Commercial construction loans | 90 Days or More
Financing Receivable, Recorded Investment, Past Due
Loans and Leases	0	0
Commercial | Commercial leases
Financing Receivable, Recorded Investment, Past Due
Loans and Leases	2,915	3,052
90 Days Past Due and Still Accruing	0	0
Commercial | Commercial leases | Current
Financing Receivable, Recorded Investment, Past Due
Loans and Leases	2,905	3,035
Commercial | Commercial leases | Total Past Due
Financing Receivable, Recorded Investment, Past Due
Loans and Leases	10	17
Commercial | Commercial leases | 30 to 89 Days
Financing Receivable, Recorded Investment, Past Due
Loans and Leases	7	16
Commercial | Commercial leases | 90 Days or More
Financing Receivable, Recorded Investment, Past Due
Loans and Leases	$ 3	$ 1