Loans and Leases - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2020		Sep. 30, 2019	Sep. 30, 2020		Sep. 30, 2019	Jun. 30, 2020	Jan. 01, 2020	Dec. 31, 2019		Jun. 30, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable
Unearned income	$ 301			$ 301					$ 354
Net premium	228			228					249
Accrued interest receivable	361			361
Loans pledged at the FHLB	15,800			15,800					16,700
Loans pledged at the FRB	35,100			35,100					47,300
Direct financing lease - interest income	16		$ 22	50		$ 70
Sales type lease - interest income	7		4	20		7
Allowance for loan and lease losses	2,574	[1]	$ 1,143	2,574	[1]	$ 1,143	$ 2,696	$ 33	1,202	[1]	$ 1,115	$ 1,103
Commercial Leases
Accounts, Notes, Loans and Financing Receivable
Allowance for loan and lease losses	$ 33			$ 33					$ 17

[1] Includes $61 and $74 of other short-term investments, $887 and $1,354 of portfolio loans and leases, $(9) and $(7) of ALLL, $5 and $8 of other assets, $2 and $2 of other liabilities, and $786 and $1,253 of long-term debt from consolidated VIEs that are included in their respective captions above at September 30, 2020 and December 31, 2019, respectively. For further information refer to Note 13.