Loans and Leases - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2024		Jun. 30, 2023	Jun. 30, 2024		Jun. 30, 2023	Mar. 31, 2024	Dec. 31, 2023		Mar. 31, 2023	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable
Unearned income	$ 289			$ 289				$ 272
Net discount	360			360				395
Accrued interest receivable	605			605				593
Direct financing lease - interest income	9		$ 7	19		$ 13
Sales type lease - interest income	19		16	37		31
Allowance for loan and lease losses	2,288	[1]	$ 2,327	2,288	[1]	$ 2,327	$ 2,318	2,322	[1]	$ 2,215	$ 2,194
Solar energy installation loans
Accounts, Notes, Loans and Financing Receivable
Net discount	881			881				865
Commercial Leases
Accounts, Notes, Loans and Financing Receivable
Allowance for loan and lease losses	14			14				13
Federal Home Loan Bank Advances
Accounts, Notes, Loans and Financing Receivable
Loans pledged	14,600			14,600				14,500
FRB Loan
Accounts, Notes, Loans and Financing Receivable
Loans pledged	$ 52,900			$ 52,900				$ 49,300

[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.