Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2019	Oct. 31, 2019
Cover [Abstract]
Entity Central Index Key	0000035527
Amendment Flag	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2019
Document Transition Report	false
Entity Registrant Name	FIFTH THIRD BANCORP
Entity File Number	001-33653
Entity Incorporation, State or Country Code	OH
Entity Tax Identification Number	31-0854434
Entity Address, Address Line One	Fifth Third Center
Entity Address, City or Town	Cincinnati
Entity Address, State or Province	OH
Entity Address, Postal Zip Code	45263
City Area Code	800
Local Phone Number	972-3030
Entity Listings [Line Items]
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		709,667,397
Common Stock, Without Par Value
Entity Listings [Line Items]
Title of 12(b) Security	Common Stock, Without Par Value
Trading Symbol	FITB
Security Exchange Name	NASDAQ
Preferred stock, Series I
Entity Listings [Line Items]
Title of 12(b) Security	6.625% Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock, Series I
Trading Symbol	FITBI
Security Exchange Name	NASDAQ
Preferred Stock, Series K
Entity Listings [Line Items]
Title of 12(b) Security	4.95% Non-Cumulative Perpetual Preferred Stock, Series K
Trading Symbol	FITBO
Security Exchange Name	NASDAQ
Class B Preferred stock, Series A
Entity Listings [Line Items]
Title of 12(b) Security	6.00% Non-Cumulative Perpetual Class B Preferred Stock, Series A
Trading Symbol	FITBP
Security Exchange Name	NASDAQ