Commitments, Contingent Liabilities and Guarantees - Additional Information (Detail) (USD $) Share data in Millions, unless otherwise specified																							3 Months Ended							3 Months Ended			12 Months Ended						12 Months Ended
	Mar. 31, 2012		Dec. 31, 2011		Mar. 31, 2011		Dec. 31, 2010	Mar. 31, 2012 Residential Mortgage	Dec. 31, 2011 Residential Mortgage	Mar. 31, 2011 Residential Mortgage	Mar. 31, 2012 Standby Letters of Credit	Dec. 31, 2011 Standby Letters of Credit	Mar. 31, 2011 Standby Letters of Credit	Mar. 31, 2012 Standby Letters of Credit Secured Debt	Dec. 31, 2011 Standby Letters of Credit Secured Debt	Mar. 31, 2011 Standby Letters of Credit Secured Debt	Mar. 31, 2012 Variable Rate Demand Note [Member]	Dec. 31, 2011 Variable Rate Demand Note [Member]	Mar. 31, 2011 Variable Rate Demand Note [Member]	Mar. 31, 2012 Other Liabilities	Dec. 31, 2011 Other Liabilities	Mar. 31, 2011 Other Liabilities	Jun. 30, 2011 Private Mortgage Reinsurance	Sep. 30, 2010 Private Mortgage Reinsurance	Mar. 31, 2012 Private Mortgage Reinsurance	Dec. 31, 2011 Private Mortgage Reinsurance	Mar. 31, 2011 Private Mortgage Reinsurance	Mar. 31, 2012 Private Mortgage Reinsurance Lower Limit	Mar. 31, 2012 Private Mortgage Reinsurance Upper Limit	Mar. 31, 2012 Visa Litigation	Jun. 30, 2011 Visa Litigation	Jun. 30, 2010 Visa Litigation	Dec. 31, 2011 Visa Litigation	Dec. 31, 2010 Visa Litigation	Dec. 31, 2009 Visa Litigation	Dec. 31, 2008 Visa Litigation	Mar. 31, 2011 Visa Litigation	Dec. 31, 2007 Visa Litigation	Dec. 31, 2009 Visa	Dec. 31, 2008 Visa
Commitments and Contingencies Disclosure [Line Items]
Reserve for unfunded commitments											$ 5,000,000	$ 5,000,000	$ 4,000,000							$ 179,000,000	$ 181,000,000	$ 211,000,000
Percentage of the total standby letters of credit											99.00%	98.00%	98.00%	51.00%	54.00%	57.00%
Fifth Third Securities, Inc. (FTS) acted as the remarketing agent to issuers of VRDNs																	2,900,000,000	2,900,000,000	3,200,000,000
Letters of credit	4,709,000,000		4,744,000,000		5,317,000,000												416,000,000	440,000,000	521,000,000
FTS held VRDN's in its portfolio and classified them as trading securities	195,000,000		177,000,000		216,000,000
Total outstanding reinsurance coverage																									74,000,000	77,000,000	122,000,000
Approximate reserve related to exposures within the reinsurance portfolio																									25,000,000	27,000,000	52,000,000
Margin account balance held by the brokerage clearing agent	18,000,000		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		2,200,000,000		2,900,000,000
Reinsurance coverage ranges of the total PMI coverage																												5.00%	10.00%
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									54,000,000
Outstanding balances on residential mortgage loans sold with representation and warranty provisions	73,000,000							55,000,000	55,000,000	73,000,000
Outstanding balances on residential mortgage loans sold with credit recourse								742,000,000	772,000,000	917,000,000
Delinquency Rates								6.40%	6.70%	7.60%
Credit loss reserve	2,126,000,000	[1]	2,255,000,000	[1]	2,805,000,000	[1]	3,004,000,000	17,000,000	17,000,000	14,000,000
Recognized liability equal to the fair value of the indemnification obligation																														49,000,000			49,000,000				31,000,000	3,000,000
Recorded share of litigation formally settled by Visa and for probable future litigation settlements																																	78,000,000		29,000,000	71,000,000	28,000,000	169,000,000
Visa IPO, shares of Visa's Class B common stock received																																								10.1
Received Class B common shares, carryover basis																																				3,000,000,000				0
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																														22,000,000					55,000,000
Visa deposited into the litigation escrow account																															400,000,000	500,000,000	1,565,000,000	800,000,000	700,000,000
Reduction of liability in cash to the swap counterparty																														75,000,000	19,000,000	20,000,000		35,000,000
Share of the Visa escrow account																																				169,000,000
Cash Proceeds Sale Of Stock																																							300,000,000
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	$ 46,477,000,000		$ 45,472,000,000		$ 43,201,000,000														$ 2,000,000

[1] Includes $19, $30 and $54 of cash, $4, $7 and $7of other short-term investments, $50, $50 and $29 of commercial mortgage loans, $217, $223 and $236 of home equity loans, $105, $259 and $529 of automobile loans, ($7), ($10) and ($12) of ALLL, $3, $4 and $5 of other assets, $3, $4 and $10 of other liabilities, $125, $191and $492 of long-term debt from consolidated VIEs that are included in their respective captions above at March 31, 2012, December 31, 2011 and March 31, 2011, respectively. See Note 8.