Credit Quality and the Allowance for Loan and Lease Losses - Summary of the Amortized Cost Basis of the Bancorp's Collateral Dependent Loans (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Financing Receivable, Impaired
Total portfolio loans and leases	$ 661	$ 1,178
Commercial
Financing Receivable, Impaired
Loans and leases receivable, allowance for amortized cost basis	534	1,018
Commercial | Commercial and industrial loans
Financing Receivable, Impaired
Loans and leases receivable, allowance for amortized cost basis	457	810
Commercial | Commercial mortgage owner-occupied loans
Financing Receivable, Impaired
Loans and leases receivable, allowance for amortized cost basis	25	101
Commercial | Commercial mortgage nonowner-occupied loans
Financing Receivable, Impaired
Loans and leases receivable, allowance for amortized cost basis	28	82
Commercial | Commercial construction loans
Financing Receivable, Impaired
Loans and leases receivable, allowance for amortized cost basis	18	19
Commercial | Commercial leases
Financing Receivable, Impaired
Loans and leases receivable, allowance for amortized cost basis	6	6
Residential Mortgage
Financing Receivable, Impaired
Loans and leases receivable, allowance for amortized cost basis	59	80
Consumer
Financing Receivable, Impaired
Loans and leases receivable, allowance for amortized cost basis	68	80
Consumer | Home equity
Financing Receivable, Impaired
Loans and leases receivable, allowance for amortized cost basis	60	71
Consumer | Indirect secured consumer loans
Financing Receivable, Impaired
Loans and leases receivable, allowance for amortized cost basis	$ 8	$ 9