Commitments, Contingent Liabilities and Guarantees - Additional Information (Detail) (USD $) Share data in Millions, unless otherwise specified	12 Months Ended								3 Months Ended		9 Months Ended		12 Months Ended
	Dec. 31, 2013		Sep. 30, 2014		Jun. 30, 2014	Sep. 30, 2013	Jun. 30, 2013	Dec. 31, 2012	Sep. 30, 2014 Residential Mortgage	Sep. 30, 2013 Residential Mortgage	Sep. 30, 2014 Residential Mortgage	Sep. 30, 2013 Residential Mortgage	Dec. 31, 2013 Residential Mortgage	Jun. 30, 2014 Residential Mortgage	Jun. 30, 2013 Residential Mortgage	Dec. 31, 2012 Residential Mortgage	Sep. 30, 2014 Secured Debt	Sep. 30, 2014 Standby Letters of Credit	Dec. 31, 2013 Standby Letters of Credit	Sep. 30, 2014 Standby Letters of Credit Secured Debt	Dec. 31, 2013 Standby Letters of Credit Secured Debt	Sep. 30, 2014 Variable Rate Demand Note	Dec. 31, 2013 Variable Rate Demand Note	Sep. 30, 2014 Variable Rate Demand Note Trading Securities	Sep. 30, 2014 Other Liabilities	Dec. 31, 2013 Other Liabilities	Sep. 30, 2014 Other Liabilities Residential Mortgage	Dec. 31, 2013 Other Liabilities Residential Mortgage	Sep. 30, 2014 Private Mortgage Reinsurance	Dec. 31, 2013 Private Mortgage Reinsurance	Sep. 30, 2014 Private Mortgage Reinsurance Lower Limit	Sep. 30, 2014 Private Mortgage Reinsurance Upper Limit	Sep. 30, 2014 Visa Litigation	Dec. 31, 2013 Visa Litigation	Dec. 31, 2009 Visa Litigation	Sep. 30, 2014 Visa	Sep. 30, 2012 Visa	Mar. 31, 2012 Visa	Jun. 30, 2011 Visa	Dec. 31, 2010 Visa	Jun. 30, 2010 Visa	Dec. 31, 2009 Visa
Loss Contingencies [Line Items]
Reserve for unfunded commitments																		$ 1,000,000	$ 2,000,000						$ 134,000,000	$ 162,000,000
Standby letters of credit as a percentage of total letters of credit																		99.00%	97.00%	63.00%	48.00%
Fifth Third Securities, Inc. (FTS) acted as the remarketing agent to issuers of VRDNs																						1,600,000,000	1,800,000,000
Letters of credit	4,129,000,000		3,931,000,000																			242,000,000	300,000,000
Total Variable Rate Demand Notes																								2,000,000
Letters of credit issued by the Bancorp related to variable rate demand notes	1,500,000,000		1,300,000,000
Total outstanding reinsurance coverage																													29,000,000	37,000,000
Approximate reserve related to exposures within the reinsurance portfolio																													3,000,000	10,000,000
Margin account balance held by the brokerage clearing agent	12,000,000		15,000,000
Fully and unconditionally guaranteed certain long-term borrowing obligations issued by wholly-owned issuing trust entities																	62,000,000
Repurchase Claim Settlement	25,000,000
Amount in excess of amounts reserved			103,000,000						46,000,000		46,000,000
Reinsurance coverage ranges of the total PMI coverage																															5.00%	10.00%
Outstanding balances on residential mortgage loans sold with representation and warranty provisions									35,000,000	103,000,000	35,000,000	103,000,000	44,000,000	36,000,000	117,000,000	110,000,000											35,000,000	44,000,000
Outstanding balances on residential mortgage loans sold with credit recourse									573,000,000		573,000,000		579,000,000
Delinquency Rates									4.00%		4.00%		4.40%
Credit loss reserve	1,582,000,000	[1]	1,414,000,000	[1]	1,458,000,000	1,677,000,000	1,735,000,000	1,854,000,000	13,000,000		13,000,000		16,000,000
Recorded share of litigation formally settled by Visa and for probable future litigation settlements																																	53,000,000	48,000,000
Visa IPO, shares of Visa's Class B common stock received																																										10.1
Received Class B common shares, carryover basis																																										0
Visa deposited into the litigation escrow account																																			3,000,000,000	450,000,000	150,000,000	1,565,000,000	400,000,000	800,000,000	500,000,000
Make Whole Payments									1,000,000	9,000,000	10,000,000	33,000,000
Repurchased Outstanding Principal									7,000,000	19,000,000	47,000,000	70,000,000
Repurchase Demand Request									24,000,000	62,000,000	84,000,000	191,000,000
Outstanding Repurchase Demand Inventory											$ 15,000,000		$ 46,000,000

[1] Includes $150 and $49 of cash and due from banks, $48 and $48 of commercial mortgage loans, $2,785 and $1,010 of automobile loans, $(19) and $(15) of ALLL, $26 and $13 of other assets, $7 and $1 of other liabilities, and $2,882 and $1,048 of long-term debt from consolidated VIEs that are included in their respective captions above at September 30, 2014 and December 31, 2013, respectively. See Note 10.