Credit Quality and the Allowance for Loan and Lease Losses - Summary of the Amortized Cost Basis of the Bancorp's Collateral Dependent Loans (Details) $ in Millions	Sep. 30, 2020 USD ($)
Financing Receivable, Impaired
Total portfolio loans and leases	$ 1,297
Commercial
Financing Receivable, Impaired
Loans and leases receivable, allowance for amortized cost basis	1,099
Commercial | Commercial and industrial loans
Financing Receivable, Impaired
Loans and leases receivable, allowance for amortized cost basis	877
Commercial | Commercial mortgage owner-occupied loans
Financing Receivable, Impaired
Loans and leases receivable, allowance for amortized cost basis	67
Commercial | Commercial mortgage nonowner-occupied loans
Financing Receivable, Impaired
Loans and leases receivable, allowance for amortized cost basis	120
Commercial | Commercial construction loans
Financing Receivable, Impaired
Loans and leases receivable, allowance for amortized cost basis	20
Commercial | Commercial leases
Financing Receivable, Impaired
Loans and leases receivable, allowance for amortized cost basis	15
Residential Mortgage
Financing Receivable, Impaired
Loans and leases receivable, allowance for amortized cost basis	114
Consumer
Financing Receivable, Impaired
Loans and leases receivable, allowance for amortized cost basis	84
Consumer | Home equity
Financing Receivable, Impaired
Loans and leases receivable, allowance for amortized cost basis	75
Consumer | Indirect secured consumer loans
Financing Receivable, Impaired
Loans and leases receivable, allowance for amortized cost basis	9
Consumer | Other consumer loans
Financing Receivable, Impaired
Loans and leases receivable, allowance for amortized cost basis	$ 0