Cover Page - USD ($)	12 Months Ended
	Dec. 31, 2019	Jan. 31, 2020	Jun. 30, 2019
Entity Listings [Line Items]
Document Type	10-K
Amendment Flag	false
Entity Central Index Key	0000035527
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--12-31
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Dec. 31, 2019
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	38 Fountain Square Plaza
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 Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
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		709,552,415
Entity Public Float			$ 18,260,843,027
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
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
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