Loans and Leases - Net Charge-Offs (Recoveries (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Assets that Continue to be Recognized, Securitized or Asset-backed Financing Arrangement Assets and any Other Financial Assets Managed Together
Net Charge-Offs	$ 71	$ 122
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	0	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	27	50
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	2	2
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	(1)	5
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	0	3
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	9	12
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	25	36
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	$ 9	$ 13