Assets and Liabilities Related to Non-consolidated VIEs and Maximum Exposure to Losses (Detail) (USD $) In Millions	Sep. 30, 2011	Dec. 31, 2010	Sep. 30, 2010
Variable Interest Entity [Line Items]
Total Assets	$ 114,905	$ 111,007	$ 112,322
Total Liabilities	101,847	96,927	98,409
Fifth Third Community Development Corporation Investments [Member] | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Total Assets	1,270	1,241	1,140
Total Liabilities	278	286	240
Maximum Exposure	1,270	1,241	1,140
Variable Interest Entity, Not Primary Beneficiary | Money Market Funds
Variable Interest Entity [Line Items]
Total Assets	61	148
Maximum Exposure	70	158
Variable Interest Entity, Not Primary Beneficiary | Loans Receivable
Variable Interest Entity [Line Items]
Total Assets	1,220	1,175	1,135
Maximum Exposure	2,001	1,908	1,684
Variable Interest Entity, Not Primary Beneficiary | Private Equity Funds
Variable Interest Entity [Line Items]
Total Assets	117	129	117
Total Liabilities		3
Maximum Exposure	295	322	293
Variable Interest Entity, Not Primary Beneficiary | Restructured Loans [Member]
Variable Interest Entity [Line Items]
Total Assets	11	12	26
Maximum Exposure	$ 13	$ 13	$ 27