Commitments, Contingent Liabilities and Guarantees - Additional Information (Detail) (USD $) Share data in Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2008	Sep. 30, 2014	Sep. 30, 2012	Mar. 31, 2012	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2010	Dec. 31, 2009
Loss Contingencies [Line Items]
Letters of credit	$ 3,974,000,000		$ 4,129,000,000
Total Variable Rate Demand Notes	1,700,000,000		2,100,000,000
Letters Credit Issued Related Variable Rate Demand Notes	1,200,000,000		1,500,000,000
Margin account balance held by the brokerage clearing agent	13,000,000		12,000,000
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	105,000,000
Credit loss reserve	1,322,000,000	[1],[2]	1,582,000,000	[1],[3]	1,854,000,000	2,255,000,000
Free-standing derivative liability initial fair value with reversal of net Visa litigation reserve	2,000,000		3,000,000
Maximum Reasonably Possible Loss Related To Mortgage Representation And Warranty Provisions In Excess Of Reserve	57,000,000
Residential Mortgage
Loss Contingencies [Line Items]
Outstanding balances on residential mortgage loans sold with representation and warranty provisions	35,000,000		44,000,000		110,000,000
Delinquency Rates	4.00%		4.40%
Credit loss reserve	11,000,000		16,000,000
Make Whole Payments	11,000,000		64,000,000
Repurchased Outstanding Principal	59,000,000		89,000,000
Repurchase Demand Request	97,000,000		263,000,000
Outstanding Repurchase Demand Inventory	7,000,000		46,000,000
Standby Letters of Credit
Loss Contingencies [Line Items]
Reserve for unfunded commitments	1,000,000		2,000,000
Standby letters of credit as a percentage of total letters of credit	97.00%		97.00%
Standby Letters of Credit | Secured Debt
Loss Contingencies [Line Items]
Standby letters of credit as a percentage of total letters of credit	60.00%		48.00%
Variable Rate Demand Note
Loss Contingencies [Line Items]
Fifth Third Securities, Inc. (FTS) acted as the remarketing agent to issuers of VRDNs	1,400,000,000		1,800,000,000
Letters of credit	247,000,000		300,000,000
Other Liabilities
Loss Contingencies [Line Items]
Reserve for unfunded commitments	135,000,000		162,000,000
Private Mortgage Reinsurance
Loss Contingencies [Line Items]
Total outstanding reinsurance coverage	29,000,000		37,000,000
Approximate reserve related to exposures within the reinsurance portfolio	2,000,000		10,000,000
Private Mortgage Reinsurance | Lower limit
Loss Contingencies [Line Items]
Reinsurance coverage ranges of the total PMI coverage	5.00%
Private Mortgage Reinsurance | Upper Limit
Loss Contingencies [Line Items]
Reinsurance coverage ranges of the total PMI coverage	10.00%
Visa Litigation
Loss Contingencies [Line Items]
Recorded share of litigation formally settled by Visa and for probable future litigation settlements	49,000,000		48,000,000
Visa deposited into the litigation escrow account							3,000,000
Visa
Loss Contingencies [Line Items]
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								$ 450,000,000	$ 150,000,000	$ 1,565,000,000	$ 400,000,000	$ 800,000,000	$ 500,000,000

[1] At December 31, 2014 and 2013, includes $179 and $49 of cash and due from banks, $47 and $48 of commercial mortgage loans, $3,331 and $1,010 of automobile loans, $(22) and $(15) of ALLL, $25 and $13 of other assets, $5 and $1 of other liabilities, $3,434 and $1,048 of long-term debt from consolidated VIEs that are included in their respective captions. For further information, refer to Note 10.

[2] Includes $6 related to leveraged leases.

[3] Includes $9 related to leveraged leases.