Assets and Liabilities Related to Non-consolidated VIEs and Maximum Exposure to Losses (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011
Variable Interest Entity [Line Items]
Total Assets	$ 116,747	$ 116,967	$ 110,485
Total Liabilities	103,137	103,716	98,293
Variable Interest Entity, Not Primary Beneficiary | Fifth Third Community Development Corporation Investments [Member]
Variable Interest Entity [Line Items]
Total Assets	1,249	1,243	1,252
Total Liabilities	265	269	278
Maximum Exposure	1,249	1,243	1,252
Variable Interest Entity, Not Primary Beneficiary | Private Equity Funds
Variable Interest Entity [Line Items]
Total Assets	166	161	98
Total Liabilities		3	2
Maximum Exposure	325	327	280
Variable Interest Entity, Not Primary Beneficiary | Money Market Funds
Variable Interest Entity [Line Items]
Total Assets	158	53	60
Maximum Exposure	165	62	70
Variable Interest Entity, Not Primary Beneficiary | Loans Receivable
Variable Interest Entity [Line Items]
Total Assets	1,568	1,370	1,170
Maximum Exposure	2,419	2,203	1,928
Variable Interest Entity, Not Primary Beneficiary | Restructured Loans [Member]
Variable Interest Entity [Line Items]
Total Assets	9	10	11
Maximum Exposure	$ 10	$ 12	$ 12