Commitments, Contingent Liabilities and Guarantees - Additional Information (Detail) (USD $) Share data in Millions, unless otherwise specified	3 Months Ended				12 Months Ended
	Dec. 31, 2011		Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010		Dec. 31, 2009	Dec. 31, 2008	Dec. 31, 2007
Commitments and Contingencies Disclosure [Line Items]
Letters of credit	$ 4,744,000,000				$ 5,516,000,000
FTS held VRDN's in its portfolio and classified them as trading securities	177,000,000				294,000,000
Margin account balance held by the brokerage clearing agent	14,000,000				10,000,000
Fully and unconditionally guaranteed certain long-term borrowing obligations issued by wholly-owned issuing trust entities	2,200,000,000				2,900,000,000
Credit loss reserve	2,255,000,000	[1]			3,004,000,000	[1]	3,749,000,000	2,787,000,000
Residential Mortgage
Commitments and Contingencies Disclosure [Line Items]
Outstanding balances on residential mortgage loans sold with representation and warranty provisions	55,000,000				85,000,000
Outstanding balances on residential mortgage loans sold with credit recourse	772,000,000				916,000,000
Delinquency Rates	6.70%				8.70%
Credit loss reserve	17,000,000				16,000,000
Standby Letters of Credit
Commitments and Contingencies Disclosure [Line Items]
Reserve for unfunded commitments	5,000,000				10,000,000
Percentage of the total standby letters of credit	98.00%				99.00%
Standby Letters of Credit | Secured Debt
Commitments and Contingencies Disclosure [Line Items]
Percentage of the total standby letters of credit	54.00%				54.00%
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	2,900,000,000				3,400,000,000
Letters of credit	440,000,000				563,000,000
Vrdns Remarketed By Third Parties Where The Agent Has Failed To Remarket The Securities					11,000,000
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
Other Liabilities
Commitments and Contingencies Disclosure [Line Items]
Reserve for unfunded commitments	181,000,000				227,000,000
Private Mortgage Reinsurance
Commitments and Contingencies Disclosure [Line Items]
Total outstanding reinsurance coverage	77,000,000				115,000,000
Approximate reserve related to exposures within the reinsurance portfolio	27,000,000				42,000,000
Collateral Release Amount			5,000,000		19,000,000
Increase (decrease) to the Bancorp's reserve liability			11,000,000		20,000,000
Increase Decrease In Maximum Exposure To Loss			27,000,000		53,000,000
Private Mortgage Reinsurance | Lower Limit
Commitments and Contingencies Disclosure [Line Items]
Reinsurance coverage ranges of the total PMI coverage	5.00%
Private Mortgage Reinsurance | Upper Limit
Commitments and Contingencies Disclosure [Line Items]
Reinsurance coverage ranges of the total PMI coverage	10.00%
Visa Litigation
Commitments and Contingencies Disclosure [Line Items]
Increase Decrease In Maximum Exposure To Loss	54,000,000
Recognized liability equal to the fair value of the indemnification obligation	49,000,000				30,000,000				3,000,000
Recorded share of litigation formally settled by Visa and for probable future litigation settlements	78,000,000				18,000,000		29,000,000	71,000,000	169,000,000
Received Class B common shares, carryover basis								3,000,000,000
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	1,565,000,000		400,000,000	500,000,000	800,000,000		700,000,000
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
Commitments and Contingencies Disclosure [Line Items]
Visa IPO, shares of Visa's Class B common stock received								10.1
Received Class B common shares, carryover basis								0
Cash Proceeds Sale Of Stock							$ 300,000,000

[1] At December 31, 2011 and 2010, includes $30 and $52 of cash, $7 of other short-term investments, $50 and $29 of commercial mortgage loans, $223 and $241 of home equity loans, $259 and $648 of automobile loans, ($10) and ($14) of ALLL, $4 and $7 of other assets, $4 and $12 of other liabilities, $191 and $692 of long-term debt from consolidated VIEs that are included in their respective captions. See Note 11.