Commitments (Commitments, Contingent Liabilities and Guarantees - Additional Information) (Detail) - USD ($) shares in Millions, $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2016	Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2013	Dec. 31, 2014	Sep. 30, 2014	Sep. 30, 2012	Mar. 31, 2012	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2010	Dec. 31, 2009
Loss Contingencies
Letters of Credit		$ 2,583		$ 3,055
Margin account balance held by the brokerage clearing agent		15		10
Repurchase Claim Settlement						$ 25
Amount in excess of amounts reserved		43
Credit loss reserve		1,253	[1]	1,272	[1]	$ 1,582	$ 1,322
Visa Class B shares carryover basis														$ 0
Residential Mortgage
Loss Contingencies
Amount in excess of amounts reserved		21
Outstanding balances on residential mortgage loans sold with representation and warranty provisions		13		25			$ 35
Outstanding balances on residential mortgage loans sold with credit recourse		$ 374		$ 465
Delinquency Rates		3.20%		3.00%
Credit loss reserve		$ 7		$ 9
Make Whole Payments		1		2
Repurchased Outstanding Principal		17		74
Repurchase Demand Request		22		75
Outstanding Repurchase Demand Inventory		2		4
Secured Debt
Loss Contingencies
Fully and unconditionally guaranteed certain long-term borrowing obligations issued by wholly-owned issuing trust entities		62		$ 62
Standby Letters of Credit
Loss Contingencies
Reserve for unfunded commitments		$ 3
Standby letters of credit as a percentage of total letters of credit		99.00%		99.00%
Standby Letters of Credit | Secured Debt
Loss Contingencies
Standby letters of credit as a percentage of total letters of credit		62.00%		65.00%
Variable Rate Demand Note
Loss Contingencies
Fifth Third Securities, Inc. (FTS) acted as the remarketing agent to issuers of VRDNs		$ 784		$ 1,100
Letters of Credit		145		187
Total Variable Rate Demand Notes		929		1,300
Letters Credit Issued Related Variable Rate Demand Notes		609		921
Variable Rate Demand Note | Trading Securities
Loss Contingencies
Total Variable Rate Demand Notes		6
Other Liabilities
Loss Contingencies
Reserve for unfunded commitments		161		138
Other Liabilities | Residential Mortgage
Loss Contingencies
Outstanding balances on residential mortgage loans sold with representation and warranty provisions		$ 13		25
Private Mortgage Reinsurance
Loss Contingencies
Total outstanding reinsurance coverage				27
Approximate reserve related to exposures within the reinsurance portfolio				2
Carrying Value Of Collateral Released To Insurer Due To Terminated Reinsurance Agreement	$ 6
Payment Received Related To The Difference Between The Release Of Assets And The Reserve Liability Assumed	$ 4
Private Mortgage Reinsurance | Lower limit
Loss Contingencies
Reinsurance coverage ranges of the total PMI coverage		5.00%
Private Mortgage Reinsurance | Upper Limit
Loss Contingencies
Reinsurance coverage ranges of the total PMI coverage		10.00%
Visa Litigation
Loss Contingencies
Recorded share of litigation formally settled by Visa and for probable future litigation settlements		$ 91		$ 61
Escrow Deposit														$ 3,000
Visa
Loss Contingencies
Visa IPO, shares of Visa's Class B common stock received														10.1
Escrow Deposit								$ 450	$ 150	$ 1,565	$ 400	$ 800	$ 500

[1] Includes $ 85 and $ 152 of cash and due from banks, $ 1,216 and $ 2,537 of portfolio loans and leases, $ (26) and $ (28) of ALLL, $ 9 and $ 14 of other assets, $ 3 and $ 3 of other liabilities and $ 1,094 and $ 2,487 of long-term debt from consolidated VIEs that are included in their respective captions above at December 31, 2016 and 2015 , respectively. For further information, refer to Note 11.