Credit Quality (Summary of the Amortized Cost Basis of the Bancorp's Collateral Dependent Loans) (Detail) $ in Millions	Mar. 31, 2020 USD ($)
Financing Receivable, Impaired
Portfolio loans and leases	$ 710
Commercial Portfolio Segment
Financing Receivable, Impaired
Loans and leases receivable allowance for amortized cost basis	543
Commercial Portfolio Segment | Commercial and Industrial Loans
Financing Receivable, Impaired
Loans and leases receivable allowance for amortized cost basis	392
Commercial Portfolio Segment | Commercial mortgage owner-occupied loans
Financing Receivable, Impaired
Loans and leases receivable allowance for amortized cost basis	43
Commercial Portfolio Segment | Commercial mortgage nonowner-occupied loans
Financing Receivable, Impaired
Loans and leases receivable allowance for amortized cost basis	88
Commercial Portfolio Segment | Commercial Construction Loans
Financing Receivable, Impaired
Loans and leases receivable allowance for amortized cost basis	1
Commercial Portfolio Segment | Commercial Leases
Financing Receivable, Impaired
Loans and leases receivable allowance for amortized cost basis	19
Residential Mortgage Loans
Financing Receivable, Impaired
Loans and leases receivable allowance for amortized cost basis	112
Consumer Portfolio Segment
Financing Receivable, Impaired
Loans and leases receivable allowance for amortized cost basis	55
Consumer Portfolio Segment | Home Equity
Financing Receivable, Impaired
Loans and leases receivable allowance for amortized cost basis	54
Consumer Portfolio Segment | Other Consumer Loans
Financing Receivable, Impaired
Loans and leases receivable allowance for amortized cost basis	$ 1