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	Jun. 30, 2023		Mar. 31, 2023	Dec. 31, 2022		Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated	$ 124			$ 122
Collectively evaluated	2,203			2,072
Total ALLL	2,327	[1]	$ 2,215	2,194	[1]	$ 2,014	$ 1,908	$ 1,892
Individually evaluated	527			1,388
Collectively evaluated	121,240			119,969
Total portfolio loans and leases	121,767			121,357
Leveraged leases	249			247
Commercial Leveraged Leases
Financing Receivable, Allowance for Credit Loss [Line Items]
Total ALLL	2			2
Leveraged leases	249			247
Commercial
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated	117			30
Collectively evaluated	1,082			1,097
Total ALLL	1,199		1,143	1,127		1,165	1,110	1,102
Individually evaluated	322			531
Collectively evaluated	76,030			75,858
Total portfolio loans and leases	76,352			76,389
Residential Mortgage
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated	1			47
Collectively evaluated	172			198
Total ALLL	173		185	245		248	239	235
Individually evaluated	132			560
Collectively evaluated	17,247			16,945
Total portfolio loans and leases	17,379			17,505
Residential mortgage loans	124			123		133
Consumer
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated	6			45
Collectively evaluated	949			777
Total ALLL	955		$ 887	822		$ 601	$ 559	$ 555
Individually evaluated	73			297
Collectively evaluated	27,963			27,166
Total portfolio loans and leases	$ 28,036			$ 27,463

[1] Includes $1 and $17 of other short-term investments, $42 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 $37 and $118 of long-term debt from consolidated VIEs that are included in their respective captions above at June 30, 2023 and December 31, 2022, respectively. For further information, refer to Note 11.