VIE (Assets and Liabilities Related to Non-consolidated VIEs and Maximum Exposure to Losses) (Detail) - Variable Interest Entity, Not Primary Beneficiary - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Fifth Third Community Development Corporation Investments
Variable Interest Entity
Total Assets	$ 1,316	$ 1,376
Total Liabilities	338	355
Maximum Exposure	1,316	1,376
Private Equity Investments
Variable Interest Entity
Total Assets	95	102
Total Liabilities	0	0
Maximum Exposure	140	150
Loans Provided to VIEs
Variable Interest Entity
Total Assets	1,937	1,845
Total Liabilities	0	0
Maximum Exposure	$ 3,043	$ 2,910