Commitments, Contingent Liabilities and Guarantees - Additional Information (Detail) (USD $)	3 Months Ended		12 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010		Dec. 31, 2009	Sep. 30, 2011		Sep. 30, 2010		Dec. 31, 2008	Dec. 31, 2007
Commitments and Contingencies Disclosure [Line Items]
Letters of credit			$ 5,516,000,000			$ 4,949,000,000		$ 5,847,000,000
VRDNs remarketed by third parties where the agent has failed to remarket the securities and has instructed the indenture trustee to draw upon letters of credit issued by the Bancorp, approximately, recorded as commercial loans in the Bancorp Condensed Consolidated Balance Sheets			43,462,000,000			44,169,000,000		42,940,000,000
FTS held VRDN's in its portfolio and classified them as trading securities			294,000,000			189,000,000		320,000,000
Total outstanding reinsurance coverage			122,000,000			92,000,000		122,000,000
Approximate reserve related to exposures within the reinsurance portfolio			42,000,000			28,000,000		37,000,000
Margin account balance held by the brokerage clearing agent						12,000,000
Fully and unconditionally guaranteed certain long-term borrowing obligations issued by wholly-owned issuing trust entities			2,900,000,000			2,300,000,000		2,800,000,000
Credit loss reserve	2,614,000,000	3,693,000,000	3,004,000,000	[1]	3,749,000,000	2,439,000,000	[1]	3,194,000,000	[1]
Recognized liability equal to the fair value of the indemnification obligation											3,000,000
Visa IPO, shares of Visa's Class B common stock received										10.1
Private Mortgage Reinsurance
Commitments and Contingencies Disclosure [Line Items]
Collateral Release Amount	5,000,000
Increase (decrease) to the Bancorp's reserve liability	11,000,000
Increase Decrease In Maximum Exposure To Loss	27,000,000
Visa Litigation
Commitments and Contingencies Disclosure [Line Items]
Recognized liability equal to the fair value of the indemnification obligation			30,000,000			31,000,000		30,000,000
Recorded share of litigation formally settled by Visa and for probable future litigation settlements					29,000,000					71,000,000	169,000,000
Visa IPO, shares of Visa's Class B common stock received										3
Sale of the Class B shares, recognition of the derivative liability and reversal of the net litigation reserve liability resulted in a pre-tax benefit					288,000,000
Sale of the Class B shares, recognition of the derivative liability and reversal of the net litigation reserve liability resulted in an after-tax benefit					187,000,000
Free-standing derivative liability initial fair value with reversal of net Visa litigation reserve					55,000,000
Visa deposited into the litigation escrow account	400,000,000	500,000,000	800,000,000		700,000,000					3,000,000,000
Reduction of liability in cash to the swap counterparty	19,000,000	20,000,000	35,000,000
Share of the Visa escrow account			199,000,000
Visa Litigation | Swap
Commitments and Contingencies Disclosure [Line Items]
Free-standing derivative liability initial fair value with reversal of net Visa litigation reserve			18,000,000			27,000,000		48,000,000
Visa
Commitments and Contingencies Disclosure [Line Items]
Received Class B common shares, carryover basis										0
Cash Proceeds Sale Of Stock					300,000,000
Other Liabilities
Commitments and Contingencies Disclosure [Line Items]
Reserve for unfunded commitments			227,000,000			187,000,000		231,000,000
Standby Letters of Credit
Commitments and Contingencies Disclosure [Line Items]
Reserve for unfunded commitments			10,000,000			2,000,000		12,000,000
Percentage of the total standby letters of credit			99.00%			98.00%		98.00%
Standby Letters of Credit | Secured Debt
Commitments and Contingencies Disclosure [Line Items]
Percentage of the total standby letters of credit			54.00%			55.00%		56.00%
Variable Rate Demand Note [Member]
Commitments and Contingencies Disclosure [Line Items]
Fifth Third Securities, Inc. (FTS) acted as the remarketing agent to issuers of VRDNs			3,400,000,000			3,000,000,000		3,700,000,000
Letters of credit			563,000,000			455,000,000		676,000,000
Purchased VRDNs from the market through FTS, held them in its trading securities portfolio								113,000,000
VRDNs remarketed by third parties where the agent has failed to remarket the securities and has instructed the indenture trustee to draw upon letters of credit issued by the Bancorp, approximately, recorded as commercial loans in the Bancorp Condensed Consolidated Balance Sheets			11,000,000					14,000,000
Variable Rate Demand Note [Member] | Fifth Third Securities Inc [Member]
Commitments and Contingencies Disclosure [Line Items]
Purchased VRDNs from the market through FTS, held them in its trading securities portfolio			105,000,000
FTS held VRDN's in its portfolio and classified them as trading securities			1,000,000			2,000,000		1,000,000
Lower Limit
Commitments and Contingencies Disclosure [Line Items]
Reinsurance coverage ranges of the total PMI coverage						5.00%
Upper Limit
Commitments and Contingencies Disclosure [Line Items]
Reinsurance coverage ranges of the total PMI coverage						10.00%
Residential Mortgage
Commitments and Contingencies Disclosure [Line Items]
Outstanding balances on residential mortgage loans sold with representation and warranty provisions			85,000,000			52,000,000		86,000,000
Outstanding balances on residential mortgage loans sold with credit recourse			916,000,000			828,000,000		971,000,000
Delinquency Rates			8.70%			7.30%		7.20%
Credit loss reserve			$ 16,000,000			$ 17,000,000		$ 17,000,000

[1] Includes $35, $52, and $56 of cash, $7, $7 and $7 of other short-term investments, $29, $29 and $29 of commercial mortgage loans, $228, $241 and $248 of home equity loans, $334, $648 and $771 of automobile loans, ($10), ($14) and ($15) of ALLL, $3, $7 and $7 of other assets, $5, $12 and $17 of other liabilities and $270, $692 and $834 of long-term debt from consolidated VIEs that are included in their respective captions above at September 30, 2011, December 31, 2010 and September 30, 2010, respectively. See Note 9.