| Document and Entity Information | Aug. 09, 2019 |
| Document And Entity Information [Line Items] | |
| Entity Registrant Name | FIFTH THIRD BANCORP |
| Amendment Flag | false |
| Entity Central Index Key | 0000035527 |
| Document Type | 8-K |
| Document Period End Date | Aug. 9, 2019 |
| Entity Incorporation, State or Country Code | OH |
| Entity File Number | 001-33653 |
| Entity Tax Identification Number | 31-0854434 |
| Entity Address, Address Line One | Fifth Third Center |
| Entity Address, Address Line Two | 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 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Common Stock, Without Par Value [Member] | |
| Document And Entity Information [Line Items] | |
| Title of 12(b) Security | Common Stock, Without Par Value |
| Trading Symbol | FITB |
| Security Exchange Name | NASDAQ |
| Series I Preferred Stock [Member] | |
| Document And Entity Information [Line Items] | |
| Title of 12(b) Security | Share of 6.625% Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock, Series I |
| Trading Symbol | FITBI |
| Security Exchange Name | NASDAQ |
