Commitments, Contingent Liabilities and Guarantees - Additional Information (Detail) (USD $) Share data in Millions, unless otherwise specified																													3 Months Ended				12 Months Ended							12 Months Ended
	Sep. 30, 2013		Jun. 30, 2013	Dec. 31, 2012		Sep. 30, 2012	Jun. 30, 2012	Dec. 31, 2011	Sep. 30, 2013 Residential Mortgage	Jun. 30, 2013 Residential Mortgage	Dec. 31, 2012 Residential Mortgage	Sep. 30, 2012 Residential Mortgage	Jun. 30, 2012 Residential Mortgage	Dec. 31, 2011 Residential Mortgage	Sep. 30, 2013 Standby Letters of Credit	Dec. 31, 2012 Standby Letters of Credit	Sep. 30, 2013 Standby Letters of Credit Secured Debt	Dec. 31, 2012 Standby Letters of Credit Secured Debt	Sep. 30, 2013 Variable Rate Demand Note	Dec. 31, 2012 Variable Rate Demand Note	Sep. 30, 2013 Other Liabilities	Dec. 31, 2012 Other Liabilities	Sep. 30, 2013 Other Liabilities Residential Mortgage	Dec. 31, 2012 Other Liabilities Residential Mortgage	Sep. 30, 2013 Private Mortgage Reinsurance	Dec. 31, 2012 Private Mortgage Reinsurance	Sep. 30, 2013 Private Mortgage Reinsurance Lower Limit	Sep. 30, 2013 Private Mortgage Reinsurance Upper Limit	Sep. 30, 2012 Visa Litigation	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	Sep. 30, 2013 Visa Litigation	Dec. 31, 2012 Visa Litigation	Dec. 31, 2007 Visa Litigation	Dec. 31, 2009 Visa	Dec. 31, 2008 Visa
Commitments and Contingencies Disclosure
Reserve for unfunded commitments															$ 2,000,000	$ 4,000,000					$ 167,000,000	$ 179,000,000
Percentage of the total standby letters of credit															98.00%	99.00%	46.00%	49.00%
Fifth Third Securities, Inc. (FTS) acted as the remarketing agent to issuers of VRDNs																			2,000,000,000	2,500,000,000
Letters of credit	4,019,000,000			4,281,000,000															299,000,000	345,000,000
Total Variable Rate Demand Notes	2,300,000,000			2,800,000,000
Letters of credit issued by the Bancorp related to variable rate demand notes	1,700,000,000			2,000,000,000
Total outstanding reinsurance coverage																									40,000,000	58,000,000
Approximate reserve related to exposures within the reinsurance portfolio																									13,000,000	18,000,000
Margin account balance held by the brokerage clearing agent	11,000,000			17,000,000
Fully and unconditionally guaranteed certain long-term borrowing obligations issued by wholly-owned issuing trust entities	812,000,000
Reinsurance coverage ranges of the total PMI coverage																											5.00%	10.00%
Increase Decrease In Maximum Exposure To Loss																																	54,000,000
Outstanding balances on residential mortgage loans sold with representation and warranty provisions	511,000,000			661,000,000					103,000,000	117,000,000	110,000,000	81,000,000	57,000,000	55,000,000									103,000,000	110,000,000
Outstanding balances on residential mortgage loans sold with credit recourse									589,000,000		662,000,000
Delinquency Rates									4.60%		5.90%
Credit loss reserve	1,677,000,000	[1]	1,735,000,000	1,854,000,000	[1]	1,925,000,000	2,016,000,000	2,255,000,000	18,000,000		20,000,000
Recognized liability equal to the fair value of the indemnification obligation																																							3,000,000
Recorded share of litigation formally settled by Visa and for probable future litigation settlements																																			29,000,000	71,000,000	35,000,000	33,000,000	169,000,000
Visa IPO, shares of Visa's Class B common stock received																																									10.1
Received Class B common shares, carryover basis																																									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																																			55,000,000
Visa deposited into the litigation escrow account																													150,000,000		400,000,000	500,000,000	1,565,000,000	800,000,000	700,000,000	3,000,000,000
Reduction of liability in cash to the swap counterparty																													6,000,000	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
Maximum Reasonably Possible Loss Related To Mortgage Representation And Warranty Provisions In Excess Of Reserve									$ 61,000,000

[1] Includes $53 and $0 of cash and due from banks, $50 and $50 of commercial mortgage loans, $1,145 and $0 of automobile loans, $(16) and $(5) of ALLL, $12 and $3 of other assets, $2 and $0 of other liabilities, and $1,198 and $0 of long-term debt from consolidated VIEs that are included in their respective captions above at September 30, 2013 and December 31, 2012, respectively. See Note 9.