Variable Interest Entities - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended									12 Months Ended				3 Months Ended
	Dec. 31, 2010 Variable Interest Entity, Primary Beneficiary Home Equity	Dec. 31, 2008 Variable Interest Entity, Primary Beneficiary Automobile Loan	Dec. 31, 2010 Variable Interest Entity, Primary Beneficiary Automobile Loan	Mar. 31, 2012 Variable Interest Entity, Primary Beneficiary Fifth Third Community Development Corporation Investments [Member]	Dec. 31, 2011 Variable Interest Entity, Primary Beneficiary Fifth Third Community Development Corporation Investments [Member]	Mar. 31, 2011 Variable Interest Entity, Primary Beneficiary Fifth Third Community Development Corporation Investments [Member]	Mar. 31, 2012 Variable Interest Entity, Not Primary Beneficiary Loans Receivable	Dec. 31, 2011 Variable Interest Entity, Not Primary Beneficiary Loans Receivable	Mar. 31, 2011 Variable Interest Entity, Not Primary Beneficiary Loans Receivable	Dec. 31, 2010 Variable Interest Entity, Not Primary Beneficiary Money Market Funds Upper Limit	Mar. 31, 2012 Variable Interest Entity, Not Primary Beneficiary Fifth Third Community Development Corporation Investments [Member]	Dec. 31, 2011 Variable Interest Entity, Not Primary Beneficiary Fifth Third Community Development Corporation Investments [Member]	Mar. 31, 2011 Variable Interest Entity, Not Primary Beneficiary Fifth Third Community Development Corporation Investments [Member]	Mar. 31, 2012 Variable Interest Entity, Not Primary Beneficiary Private Equity Funds	Mar. 31, 2011 Variable Interest Entity, Not Primary Beneficiary Private Equity Funds	Dec. 31, 2011 Variable Interest Entity, Not Primary Beneficiary Private Equity Funds	Mar. 31, 2012 Variable Interest Entity, Not Primary Beneficiary Restructured Loans	Dec. 31, 2011 Variable Interest Entity, Not Primary Beneficiary Restructured Loans	Mar. 31, 2011 Variable Interest Entity, Not Primary Beneficiary Restructured Loans
Variable Interest Entity [Line Items]
Carry Value Of Loans Leases Or Lines Of Credit Securitized	$ 903	$ 2,700
Number of seperate transactions in which the Bancorp previously sold loans to an isolated trust and conduits			3
Maximum Exposure				16	10	9					1,249	1,243	1,252	325	280	327	10	12	12
Equity investments, fair value																		0
Unfunded commitment amounts							851	833	758					159	182	166	1	2	1
Capital Contribution To Private Equity Funds														11	10
Credit support										$ 1