Assets and Liabilities Related to Non-consolidated VIEs and Maximum Exposure to Losses (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011
Variable Interest Entity [Line Items]
Total Assets	$ 117,483	$ 116,967	$ 114,905
Total Liabilities	103,714	103,716	101,847
Variable Interest Entity, Not Primary Beneficiary | Fifth Third Community Development Corporation Investments [Member]
Variable Interest Entity [Line Items]
Total Assets	1,386	1,243	1,270
Total Liabilities	374	269	278
Maximum Exposure	1,386	1,243	1,270
Variable Interest Entity, Not Primary Beneficiary | Private Equity Funds
Variable Interest Entity [Line Items]
Total Assets	187	161	117
Total Liabilities	12	3
Maximum Exposure	324	327	295
Variable Interest Entity, Not Primary Beneficiary | Money Market Funds
Variable Interest Entity [Line Items]
Total Assets		53	61
Maximum Exposure		62	70
Variable Interest Entity, Not Primary Beneficiary | Loans Receivable
Variable Interest Entity [Line Items]
Total Assets	1,545	1,370	1,220
Maximum Exposure	2,335	2,203	2,001
Variable Interest Entity, Not Primary Beneficiary | Restructured Loans [Member]
Variable Interest Entity [Line Items]
Total Assets	6	10	11
Maximum Exposure	$ 6	$ 12	$ 13