| Document and Entity Information | Nov. 12, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Nov. 12, 2021 |
| Entity Registrant Name | Iterum Therapeutics plc |
| Entity Central Index Key | 0001659323 |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | true |
| Entity File Number | 001-38503 |
| Entity Incorporation, State or Country Code | L2 |
| Entity Tax Identification Number | 98-1283148 |
| Entity Address, Address Line One | Fitzwilliam Court |
| Entity Address, Address Line Two | 1st Floor |
| Entity Address, Address Line Three | Leeson Close |
| Entity Address, City or Town | Dublin 2 |
| Entity Address, Country | IE |
| Entity Address, Postal Zip Code | Not Applicable |
| City Area Code | +353 |
| Local Phone Number | 1 669 4820 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Ordinary Shares, par value $0.01 per share |
| Trading Symbol | ITRM |
| Security Exchange Name | NASDAQ |
