Credit Quality and the Allowance for Loan and Lease Losses - Summary of the ALLL and Related Loans and Leases Classified by Portfolio Segment (Details) - USD ($) $ in Millions	Mar. 31, 2023		Dec. 31, 2022		Mar. 31, 2022	Dec. 31, 2021
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated	$ 80		$ 122
Collectively evaluated	2,135		2,072
Total ALLL	2,215	[1]	2,194	[1]	$ 1,908	$ 1,892
Individually evaluated	460		1,388
Collectively evaluated	122,269		119,969
Total portfolio loans and leases	122,729		121,357
Leveraged leases	248		247
Commercial Leveraged Leases
Financing Receivable, Allowance for Credit Loss [Line Items]
Total ALLL	2		2
Leveraged leases	248		247
Commercial
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated	78		30
Collectively evaluated	1,065		1,097
Total ALLL	1,143		1,127		1,110	1,102
Individually evaluated	319		531
Collectively evaluated	76,920		75,858
Total portfolio loans and leases	77,239		76,389
Residential Mortgage
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated	0		47
Collectively evaluated	185		198
Total ALLL	185		245		239	235
Individually evaluated	92		560
Collectively evaluated	17,388		16,945
Total portfolio loans and leases	17,480		17,505
Residential mortgage loans	128		123		145
Consumer
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated	2		45
Collectively evaluated	885		777
Total ALLL	887		822		$ 559	$ 555
Individually evaluated	49		297
Collectively evaluated	27,961		27,166
Total portfolio loans and leases	$ 28,010		$ 27,463

[1] Includes $5 and $17 of other short-term investments, $44 and $185 of portfolio loans and leases, $(1) and $(2) of ALLL, $0 and $2 of other assets, $9 and $9 of other liabilities, and $38 and $118 of long-term debt from consolidated VIEs that are included in their respective captions above at March 31, 2023 and December 31, 2022, respectively. For further information, refer to Note 12.