Loans and Leases - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2023		Sep. 30, 2022	Sep. 30, 2023		Sep. 30, 2022	Jun. 30, 2023	Dec. 31, 2022		Jun. 30, 2022	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable
Unearned income	$ 276			$ 276				$ 238
Unamortized premium (discount)	(339)			(339)				146
Accrued interest receivable	584			584				518
Direct financing lease - interest income	7		$ 7	20		$ 22
Sales type lease - interest income	16		13	47		36
Allowance for loan and lease losses	2,340	[1]	$ 2,099	2,340	[1]	$ 2,099	$ 2,327	2,194	[1]	$ 2,014	$ 1,892
Commercial Leases
Accounts, Notes, Loans and Financing Receivable
Allowance for loan and lease losses	16			16				15
Federal Home Loan Bank Advances
Accounts, Notes, Loans and Financing Receivable
Loans pledged	14,800			14,800				15,900
FRB Loan
Accounts, Notes, Loans and Financing Receivable
Loans pledged	$ 51,500			$ 51,500				$ 57,100

[1] 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.