Credit Quality (Summarizes the Bancorp's Recorded Investment in Impaired Loans and Related Allowance by Class) (Detail) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Impaired Financing Receivable Unpaid Principal Balance
Impaired Financing Receivable With Related Allowance Unpaid Principal Balance	$ 917	$ 1,158
Impaired Financing Receivable With No Related Allowance Unpaid Principal Balance	575	521
Unpaid Principal Balance	1,492	1,679
Impaired Financing Receivable Recorded Investment Abstract
Impaired Financing Receivable With Related Allowance Recorded Investment	861	1,068
Impaired Financing Receivable With No Related Allowance Recorded Investment	526	477
Recorded investment	1,387	1,545
Allowance	168	200
Commercial Portfolio Segment | Commercial and Industrial Loans
Impaired Financing Receivable Unpaid Principal Balance
Impaired Financing Receivable With Related Allowance Unpaid Principal Balance	199	433
Impaired Financing Receivable With No Related Allowance Unpaid Principal Balance	171	151
Impaired Financing Receivable Recorded Investment Abstract
Impaired Financing Receivable With Related Allowance Recorded Investment	150	358
Impaired Financing Receivable With No Related Allowance Recorded Investment	148	131
Allowance	55	87
Commercial Portfolio Segment | Commercial Mortgage Loans, Owner-occupied
Impaired Financing Receivable Unpaid Principal Balance
Impaired Financing Receivable With Related Allowance Unpaid Principal Balance	2	16
Impaired Financing Receivable With No Related Allowance Unpaid Principal Balance	8	18
Impaired Financing Receivable Recorded Investment Abstract
Impaired Financing Receivable With Related Allowance Recorded Investment	2	14
Impaired Financing Receivable With No Related Allowance Recorded Investment	5	15
Allowance	1	7
Commercial Portfolio Segment | Commercial Mortgage Loans, Nonowner-Occupied
Impaired Financing Receivable Unpaid Principal Balance
Impaired Financing Receivable With Related Allowance Unpaid Principal Balance	1	4
Impaired Financing Receivable With No Related Allowance Unpaid Principal Balance	13	35
Impaired Financing Receivable Recorded Investment Abstract
Impaired Financing Receivable With Related Allowance Recorded Investment	1	3
Impaired Financing Receivable With No Related Allowance Recorded Investment	12	35
Allowance	0	0
Commercial Portfolio Segment | Commercial Leases
Impaired Financing Receivable Unpaid Principal Balance
Impaired Financing Receivable With Related Allowance Unpaid Principal Balance	27	4
Impaired Financing Receivable Recorded Investment Abstract
Impaired Financing Receivable With Related Allowance Recorded Investment	27	4
Allowance	10	0
Residential Mortgage Loans
Impaired Financing Receivable Unpaid Principal Balance
Impaired Financing Receivable With Related Allowance Unpaid Principal Balance	484	469
Impaired Financing Receivable With No Related Allowance Unpaid Principal Balance	294	218
Impaired Financing Receivable Recorded Investment Abstract
Impaired Financing Receivable With Related Allowance Recorded Investment	481	465
Impaired Financing Receivable With No Related Allowance Recorded Investment	276	200
Allowance	64	64
Consumer Portfolio Segment | Home Equity
Impaired Financing Receivable Unpaid Principal Balance
Impaired Financing Receivable With Related Allowance Unpaid Principal Balance	152	172
Impaired Financing Receivable With No Related Allowance Unpaid Principal Balance	87	97
Impaired Financing Receivable Recorded Investment Abstract
Impaired Financing Receivable With Related Allowance Recorded Investment	152	172
Impaired Financing Receivable With No Related Allowance Recorded Investment	84	94
Allowance	22	27
Consumer Portfolio Segment | Automobile Loans
Impaired Financing Receivable Unpaid Principal Balance
Impaired Financing Receivable With Related Allowance Unpaid Principal Balance	5	8
Impaired Financing Receivable With No Related Allowance Unpaid Principal Balance	2	2
Impaired Financing Receivable Recorded Investment Abstract
Impaired Financing Receivable With Related Allowance Recorded Investment	5	7
Impaired Financing Receivable With No Related Allowance Recorded Investment	1	2
Allowance	1	1
Consumer Portfolio Segment | Credit Card
Impaired Financing Receivable Unpaid Principal Balance
Impaired Financing Receivable With Related Allowance Unpaid Principal Balance	47	52
Impaired Financing Receivable Recorded Investment Abstract
Impaired Financing Receivable With Related Allowance Recorded Investment	43	45
Allowance	$ 15	$ 14