Commitments (Commitments, Contingent Liabilities and Guarantees - Additional Information) (Detail) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2019		Mar. 31, 2018	Dec. 31, 2018		Jun. 30, 2018	Dec. 31, 2017	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	$ 2,196			$ 2,041
Margin account balance held by the brokerage clearing agent	13			13
Amount in excess of amounts reserved	54
Credit loss reserve	1,115	[1]	$ 1,138	1,103	[1]		$ 1,196
Residential Mortgage
Loss Contingencies
Amount in excess of amounts reserved	11
Outstanding balances on residential mortgage loans sold with representation and warranty provisions	8		8	6			$ 9
Outstanding Repurchase Demand Inventory	6			1
Outstanding balances on residential mortgage loans sold with credit recourse	$ 260			$ 272
Delinquency Rates	2.00%			2.20%
Credit loss reserve	$ 4			$ 5
Repurchased Outstanding Principal	9		2
Repurchase Demand Request	18		$ 5
Secured Debt
Loss Contingencies
Fully and unconditionally guaranteed certain long-term borrowing obligations issued by wholly-owned issuing trust entities	183			62
Standby Letters of Credit
Loss Contingencies
Reserve for unfunded commitments	$ 24			$ 17
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%			60.00%
Variable Rate Demand Note
Loss Contingencies
Fifth Third Securities, Inc. (FTS) acted as the remarketing agent to issuers of VRDNs	$ 441			$ 481
Letters of credit	6			6
Total Variable Rate Demand Notes	447			487
Letters of credit issued by the Bancorp related to variable rate demand notes	248			256
Variable Rate Demand Note | Trading Securities
Loss Contingencies
Total Variable Rate Demand Notes	1			9
Other Liabilities
Loss Contingencies
Reserve for unfunded commitments	133			131
Visa
Loss Contingencies
Recorded share of litigation formally settled by Visa and for probable future litigation settlements	$ 143			$ 125
Visa IPO, shares of Visa's Class B common stock received														10.1
Visa Class B shares carryover basis														$ 0
Escrow Deposit						$ 600		$ 450	$ 150	$ 1,565	$ 400	$ 800	$ 500	$ 3,000

[1] Includes $ 39 and $ 40 of other short-term investments , $ 573 and $ 668 of portfolio loans and leases, $ (3) and $ (4) of ALLL, $ 3 and $ 5 of other assets, $ 1 and $ 1 of other liabilities, and $ 510 and $ 606 of long-term debt from consolidated VIEs that are included in their respe ctive captions above at March 31, 2019 and December 31, 2018 , respectively. For further information refer to Note 13 .