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, 2024	Dec. 31, 2023
Financing Receivable, Impaired
Total portfolio loans and leases	$ 491	$ 474
Commercial
Financing Receivable, Impaired
Loans and leases receivable, allowance for amortized cost basis	274	279
Commercial | Commercial and industrial loans
Financing Receivable, Impaired
Loans and leases receivable, allowance for amortized cost basis	206	268
Commercial | Commercial mortgage owner-occupied loans
Financing Receivable, Impaired
Loans and leases receivable, allowance for amortized cost basis	63	8
Commercial | Commercial mortgage nonowner-occupied loans
Financing Receivable, Impaired
Loans and leases receivable, allowance for amortized cost basis	4	2
Commercial | Commercial construction loans
Financing Receivable, Impaired
Loans and leases receivable, allowance for amortized cost basis	1	1
Residential Mortgage
Financing Receivable, Impaired
Loans and leases receivable, allowance for amortized cost basis	130	126
Consumer
Financing Receivable, Impaired
Loans and leases receivable, allowance for amortized cost basis	87	69
Consumer | Home equity
Financing Receivable, Impaired
Loans and leases receivable, allowance for amortized cost basis	62	54
Consumer | Indirect secured consumer loans
Financing Receivable, Impaired
Loans and leases receivable, allowance for amortized cost basis	$ 25	$ 15