Credit Quality (Summarizes the Bancorp's Recorded Investment in Impaired Loans and Related Allowance by Class) (Parenthetical) (Detail) $ in Millions	3 Months Ended				12 Months Ended
	Mar. 31, 2018 USD ($)		Mar. 31, 2017		Dec. 31, 2017 USD ($)
Financing Receivable, Impaired
Unpaid principal balance	$ 1,665				$ 1,679
Recorded investment	1,547	[1]			1,545	[2]
Allowance	$ 217				200
Number of contracts	2,271	[3],[4]	2,059	[5],[6]
Commercial Portfolio Segment | Commercial Mortgage Loans, Owner-occupied
Financing Receivable, Impaired
Allowance	$ 1				$ 7
Number of contracts	2	[3],[4]	5	[5],[6]
Commercial Portfolio Segment | Commercial Mortgage Loans, Owner-occupied | Variable Interest Entity, Primary Beneficiary
Financing Receivable, Impaired
Number of contracts			5		5
Commercial Portfolio Segment | Troubled Debt Restructuring On Accrual Status
Financing Receivable, Impaired
Recorded investment	$ 249				$ 249
Commercial Portfolio Segment | Troubled Debt Restructuring On Nonaccrual Status
Financing Receivable, Impaired
Recorded investment	154				150
Residential Mortgage Loans
Financing Receivable, Impaired
Allowance	$ 64				64
Number of contracts	247	[3],[4]	203	[5],[6]
Residential Mortgage Loans | Troubled Debt Restructuring On Accrual Status
Financing Receivable, Impaired
Recorded investment	$ 654				652
Residential Mortgage Loans | Troubled Debt Restructuring On Nonaccrual Status
Financing Receivable, Impaired
Recorded investment	12				13
Consumer Portfolio Segment | Troubled Debt Restructuring On Accrual Status
Financing Receivable, Impaired
Recorded investment	262				275
Consumer Portfolio Segment | Troubled Debt Restructuring On Nonaccrual Status
Financing Receivable, Impaired
Recorded investment	$ 46				$ 45

[1] Includes $ 249 , $ 654 and $ 262 , respectively, of commercial, residential mortgage and consumer portfolio TDRs on accrual status and $ 154 , $ 12 an d $ 46 , respectively, of commercial, re sidential mortgage and consumer portfolio TDRs on nonaccrual status at March 31, 2018 .

[2] Includes $ 249 , $ 652 and $ 275 , respectively, of commercial, residential mortgage and consumer portfolio TDR s on accrual status and $ 150 , $ 13 and $ 45 , respectively , of commercial, residential mortgage and consumer portfolio TDRs on nonaccrual status at December 31, 2017 .

[3] Represents number of loans post-modification and excludes loans previously modified in a TDR .

[4] Excludes all loans and leases held for sale and loans acquired with deteriorated credit quality which were accounted for within a pool .

[5] Represents number of loans post-modification and excludes loans previously modified in a TDR .

[6] Excludes all loans and leases held for sale and loans acquired with deteriorated credit quality which were accounted for within a pool .