VIE (Variable Interest Entities - Additional Information) (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Variable Interest Entity
OTTI	[1]	$ 16	$ 5	$ 24
Private equity investments
Variable Interest Entity
Private Equity Fund Impairment		9	1	0
Variable Interest Entity, Primary Beneficiary | Automobile Loans
Variable Interest Entity
Carry Value Of Loans Leases Or Lines Of Credit Securitized			750	3,800
Variable Interest Entity, Primary Beneficiary | Fifth Third Community Development Corporation Investments
Variable Interest Entity
Maximum Exposure		31	27
Variable Interest Entity, Not Primary Beneficiary | Loans Provided to VIEs
Variable Interest Entity
Unfunded commitment amounts		937	969
Variable Interest Entity, Not Primary Beneficiary | Fifth Third Community Development Corporation Investments
Variable Interest Entity
Maximum Exposure		1,421	1,455
Bancorp's Investment in Affordable Housing Tax Credits		1,421	1,455
Variable Interest Entity, Not Primary Beneficiary | Fifth Third Community Development Corporation Investments | Qualified Affordable Housing Tax Credits
Variable Interest Entity
Bancorp's Investment in Affordable Housing Tax Credits		1,300	1,300
Unfunded commitments		$ 349	356
Unfunded commitments expected funding date		2033
Variable Interest Entity, Not Primary Beneficiary | Private equity investments
Variable Interest Entity
Maximum Exposure		$ 232	271
Bancorp's Investment in Affordable Housing Tax Credits		176	211
Unfunded commitment amounts		56	60
Capital Contribution To Private Equity Investments		14	30
OTTI		$ 9	$ 1	$ 0

[1] (a) Included in securiti es gains, net, in the Consolidated Statements of Income .