Credit Quality (Summary of the Credit Risk Profile of the Bancorp's Commercial Portfolio Segment by Class) (Detail) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Financing Receivable, Modifications
Total loans and leases	$ 93,271	$ 91,833
Commercial and Industrial Loans
Financing Receivable, Modifications
Total loans and leases	42,631	41,170
Commercial Mortgage Loans, Owner-occupied
Financing Receivable, Modifications
Total loans and leases	3,324	3,362
Commercial Mortgage Loans, Nonowner-Occupied
Financing Receivable, Modifications
Total loans and leases	3,371	3,242
Commercial Construction Loans
Financing Receivable, Modifications
Total loans and leases	4,892	4,553
Commercial Leases
Financing Receivable, Modifications
Total loans and leases	3,697	4,068
Commercial Portfolio Segment
Financing Receivable, Modifications
Total loans and leases	57,915	56,395
Commercial Portfolio Segment | Commercial and Industrial Loans
Financing Receivable, Modifications
Total loans and leases	42,631	41,170
Commercial Portfolio Segment | Commercial Mortgage Loans, Owner-occupied
Financing Receivable, Modifications
Total loans and leases	3,324	3,362
Commercial Portfolio Segment | Commercial Mortgage Loans, Nonowner-Occupied
Financing Receivable, Modifications
Total loans and leases	3,371	3,242
Commercial Portfolio Segment | Commercial Construction Loans
Financing Receivable, Modifications
Total loans and leases	4,892	4,553
Commercial Portfolio Segment | Commercial Leases
Financing Receivable, Modifications
Total loans and leases	3,697	4,068
Pass | Commercial Portfolio Segment
Financing Receivable, Modifications
Total loans and leases	55,916	53,612
Pass | Commercial Portfolio Segment | Commercial and Industrial Loans
Financing Receivable, Modifications
Total loans and leases	41,008	38,813
Pass | Commercial Portfolio Segment | Commercial Mortgage Loans, Owner-occupied
Financing Receivable, Modifications
Total loans and leases	3,162	3,207
Pass | Commercial Portfolio Segment | Commercial Mortgage Loans, Nonowner-Occupied
Financing Receivable, Modifications
Total loans and leases	3,316	3,117
Pass | Commercial Portfolio Segment | Commercial Construction Loans
Financing Receivable, Modifications
Total loans and leases	4,892	4,553
Pass | Commercial Portfolio Segment | Commercial Leases
Financing Receivable, Modifications
Total loans and leases	3,538	3,922
Special Mention | Commercial Portfolio Segment
Financing Receivable, Modifications
Total loans and leases	940	1,290
Special Mention | Commercial Portfolio Segment | Commercial and Industrial Loans
Financing Receivable, Modifications
Total loans and leases	776	1,115
Special Mention | Commercial Portfolio Segment | Commercial Mortgage Loans, Owner-occupied
Financing Receivable, Modifications
Total loans and leases	50	75
Special Mention | Commercial Portfolio Segment | Commercial Mortgage Loans, Nonowner-Occupied
Financing Receivable, Modifications
Total loans and leases	40	28
Special Mention | Commercial Portfolio Segment | Commercial Construction Loans
Financing Receivable, Modifications
Total loans and leases	0	0
Special Mention | Commercial Portfolio Segment | Commercial Leases
Financing Receivable, Modifications
Total loans and leases	74	72
Substandard | Commercial Portfolio Segment
Financing Receivable, Modifications
Total loans and leases	1,059	1,486
Substandard | Commercial Portfolio Segment | Commercial and Industrial Loans
Financing Receivable, Modifications
Total loans and leases	847	1,235
Substandard | Commercial Portfolio Segment | Commercial Mortgage Loans, Owner-occupied
Financing Receivable, Modifications
Total loans and leases	112	80
Substandard | Commercial Portfolio Segment | Commercial Mortgage Loans, Nonowner-Occupied
Financing Receivable, Modifications
Total loans and leases	15	97
Substandard | Commercial Portfolio Segment | Commercial Construction Loans
Financing Receivable, Modifications
Total loans and leases	0	0
Substandard | Commercial Portfolio Segment | Commercial Leases
Financing Receivable, Modifications
Total loans and leases	85	74
Doubtful | Commercial Portfolio Segment
Financing Receivable, Modifications
Total loans and leases	0	7
Doubtful | Commercial Portfolio Segment | Commercial and Industrial Loans
Financing Receivable, Modifications
Total loans and leases	0	7
Doubtful | Commercial Portfolio Segment | Commercial Mortgage Loans, Owner-occupied
Financing Receivable, Modifications
Total loans and leases	0	0
Doubtful | Commercial Portfolio Segment | Commercial Mortgage Loans, Nonowner-Occupied
Financing Receivable, Modifications
Total loans and leases	0	0
Doubtful | Commercial Portfolio Segment | Commercial Construction Loans
Financing Receivable, Modifications
Total loans and leases	0	0
Doubtful | Commercial Portfolio Segment | Commercial Leases
Financing Receivable, Modifications
Total loans and leases	$ 0	$ 0