Commitments (Commitments, Contingent Liabilities and Guarantees - Additional Information) (Detail) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2018		Dec. 31, 2017		Jun. 30, 2018	Dec. 31, 2016	Dec. 31, 2015	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	$ 2,041		$ 2,185
Margin account balance held by the brokerage clearing agent	13		15
Amount in excess of amounts reserved	14
Credit loss reserve	1,103	[1]	1,196	[1]		$ 1,253	$ 1,272
Visa Class B shares carryover basis														$ 0
Residential Mortgage
Loss Contingencies
Amount in excess of amounts reserved	9
Outstanding balances on residential mortgage loans sold with representation and warranty provisions	6		9			$ 13
Outstanding balances on residential mortgage loans sold with credit recourse	$ 272		$ 312
Delinquency Rates	2.20%		3.00%
Credit loss reserve	$ 5		$ 5
Make Whole Payments			1
Repurchased Outstanding Principal	18		12
Repurchase Demand Request	19		15
Outstanding Repurchase Demand Inventory	1		1
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	$ 17		$ 6
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	60.00%		61.00%
Variable Rate Demand Note
Loss Contingencies
Fifth Third Securities, Inc. (FTS) acted as the remarketing agent to issuers of VRDNs	$ 481		$ 508
Letters of Credit	6		94
Total Variable Rate Demand Notes	487		602
Letters Credit Issued Related Variable Rate Demand Notes	256		331
Variable Rate Demand Note | TradingAssetsExcludingDebtAndEquitySecuritiesMember [Member]
Loss Contingencies
Total Variable Rate Demand Notes	9		1
Other Liabilities
Loss Contingencies
Reserve for unfunded commitments	131		161
Other Liabilities | Residential Mortgage
Loss Contingencies
Outstanding balances on residential mortgage loans sold with representation and warranty provisions	6		9
Visa
Loss Contingencies
Recorded share of litigation formally settled by Visa and for probable future litigation settlements	$ 125		$ 137
Visa IPO, shares of Visa's Class B common stock received														10.1
Escrow Deposit					$ 600			$ 450	$ 150	$ 1,565	$ 400	$ 800	$ 500	$ 3,000

[1] Includes $ 40 and $ 62 of other short-term investments, $ 668 and $ 1,297 of portfolio loans and leases, $ (4) and $ (6) of ALLL, $ 5 and $ 7 of other assets, $ 1 and $ 2 of other liabilities and $ 606 and $ 1,190 of long-term debt from consolidated VIEs that are included in their respec tive captions above at December 31, 2018 and 2017 , respectively. For further information, refer to Note 10 .