VIE (Assets and Liabilities Related to Non-consolidated VIEs and Maximum Exposure to Losses) (Detail) - Variable Interest Entity, Not Primary Beneficiary - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Fifth Third Community Development Corporation Investments
Variable Interest Entity
Total Assets	$ 1,213	$ 1,376
Total Liabilities	363	355
Maximum Exposure	1,213	1,376
Private Equity Investments
Variable Interest Entity
Total Assets	70	102
Total Liabilities	0	0
Maximum Exposure	112	150
Loans Provided to VIEs
Variable Interest Entity
Total Assets	1,885	1,845
Total Liabilities	0	0
Maximum Exposure	$ 3,124	$ 2,910