Loans and Leases - Net Charge-Offs (Recoveries) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Assets that Continue to be Recognized, Securitized or Asset-backed Financing Arrangement Assets and any Other Financial Assets Managed Together
Net charge-offs (recoveries)	$ 21	$ 101	$ 136	$ 353
Residential mortgage loans
Assets that Continue to be Recognized, Securitized or Asset-backed Financing Arrangement Assets and any Other Financial Assets Managed Together
Net charge-offs (recoveries)	(1)	(1)	(2)	1
Commercial | Commercial and industrial loans
Assets that Continue to be Recognized, Securitized or Asset-backed Financing Arrangement Assets and any Other Financial Assets Managed Together
Net charge-offs (recoveries)	5	42	45	157
Commercial | Commercial mortgage loans
Assets that Continue to be Recognized, Securitized or Asset-backed Financing Arrangement Assets and any Other Financial Assets Managed Together
Net charge-offs (recoveries)	(1)	11	8	14
Commercial | Commercial leases
Assets that Continue to be Recognized, Securitized or Asset-backed Financing Arrangement Assets and any Other Financial Assets Managed Together
Net charge-offs (recoveries)	0	8	(2)	24
Consumer | Home equity
Assets that Continue to be Recognized, Securitized or Asset-backed Financing Arrangement Assets and any Other Financial Assets Managed Together
Net charge-offs (recoveries)	(1)	1	(2)	5
Consumer | Indirect secured consumer loans
Assets that Continue to be Recognized, Securitized or Asset-backed Financing Arrangement Assets and any Other Financial Assets Managed Together
Net charge-offs (recoveries)	(1)	3	8	23
Consumer | Credit card
Assets that Continue to be Recognized, Securitized or Asset-backed Financing Arrangement Assets and any Other Financial Assets Managed Together
Net charge-offs (recoveries)	12	29	57	100
Consumer | Other consumer loans
Assets that Continue to be Recognized, Securitized or Asset-backed Financing Arrangement Assets and any Other Financial Assets Managed Together
Net charge-offs (recoveries)	$ 8	$ 8	$ 24	$ 29