Quarterly report pursuant to Section 13 or 15(d)

Basis of Presentation - Additional Information (Details)

v3.20.2
Basis of Presentation - Additional Information (Details)
1 Months Ended 3 Months Ended 9 Months Ended 12 Months Ended
Nov. 02, 2020
USD ($)
$ / shares
shares
Oct. 31, 2020
USD ($)
$ / shares
shares
Oct. 27, 2020
USD ($)
$ / shares
shares
Oct. 22, 2020
$ / shares
shares
Jul. 02, 2020
$ / shares
shares
Jun. 05, 2020
$ / shares
shares
Jun. 03, 2020
USD ($)
$ / shares
shares
Apr. 30, 2020
USD ($)
Jan. 21, 2020
USD ($)
Debtinstrument
$ / shares
shares
Jun. 30, 2020
USD ($)
$ / shares
shares
Sep. 30, 2020
USD ($)
$ / shares
shares
Sep. 30, 2019
USD ($)
Sep. 30, 2020
USD ($)
$ / shares
shares
Sep. 30, 2019
USD ($)
Dec. 31, 2019
USD ($)
$ / shares
shares
Sep. 08, 2020
USD ($)
Jul. 16, 2019
USD ($)
Organization Consolidation And Presentation Of Financial Statements [Line Items]                                  
Description of deferring payment on US payroll taxes                         In April 2020, the Company began deferring payment on its share of U.S. payroll taxes owed, as allowed by the Coronavirus Aid, Relief and Economic Security Act (CARES Act) through December 31, 2020. The Company is able to defer half of its share of U.S. payroll taxes owed until December 31, 2021, with the remaining half due on December 31, 2022        
Ordinary shares, shares issued | shares                     21,239,093   21,239,093   14,868,973    
Ordinary shares, par value | $ / shares                     $ 0.01   $ 0.01   $ 0.01    
Proceeds from registered direct offerings, net of transaction costs                         $ 8,560,000        
Net losses                     $ 12,199,000 $ 31,271,000 40,820,000 $ 79,489,000 $ 103,130,000    
Accumulated deficit                     $ 275,743,000   $ 275,743,000   $ 234,923,000    
June 3 SPA                                  
Organization Consolidation And Presentation Of Financial Statements [Line Items]                                  
Warrants to purchase ordinary shares, exercise price | $ / shares                     $ 0.01   $ 0.01        
June 30 SPA                                  
Organization Consolidation And Presentation Of Financial Statements [Line Items]                                  
Warrants to purchase ordinary shares, exercise price | $ / shares                     $ 0.01   $ 0.01        
Iterum Therapeutics US Limited | Silicon Valley Bank (SVB) | Paycheck Protection Program                                  
Organization Consolidation And Presentation Of Financial Statements [Line Items]                                  
Aggregate principal amount               $ 744,000                  
Debt instrument interest rate               1.00%                  
Debt instrument maturity period               2 years                  
Minimum percentage of loan proceeds used for payroll costs               60.00%                  
Debt instrument, description               Under the terms of the agreement, there shall be no payments due by the Company until the later of the date the SBA remits the forgiveness amount to the borrower or 10 months after the end of the six-month period beginning April 30, 2020 (the Deferral Period). Following the Deferral Period, equal monthly repayments of principal and interest will be due to fully amortize the principal amount outstanding on the PPP loan on the last day of the Deferral Period by the maturity date. Under the terms of the Program, the SBA will forgive the portion of loan proceeds used for U.S. payroll costs and other designated operating expenses for up to 24 weeks, provided at least 60% of the loan proceeds are used for U.S. payroll costs. The Company incurred qualifying payroll costs and other operating expenses in the 24 weeks following April 30, 2020, and has requested forgiveness for a portion of the PPP loan from the Lender         Under the terms of the agreement, there shall be no payments due by the Company until the later of the date the SBA remits the forgiveness amount to the borrower or 10 months after the end of the six-month period beginning April 30, 2020 (the Deferral Period). Following the Deferral Period, equal monthly repayments of principal and interest will be due to fully amortize the principal amount outstanding on the note on the last day of the Deferral Period by the maturity date. Under the terms of the Program, the SBA will forgive the portion of loan proceeds used for payroll costs and other designated operating expenses for up to 24 weeks, provided at least 60% of the loan proceeds are used for payroll costs. The Company incurred qualifying payroll costs and other operating expenses in the 24 weeks from April 30, 2020, and has requested forgiveness for a portion of the loan from the Lender        
Maximum                                  
Organization Consolidation And Presentation Of Financial Statements [Line Items]                                  
Aggregate initial offering price of securities authorized to issue                                 $ 150,000,000
Private Placement and Rights Offering | 2025 Exchangeable Notes                                  
Organization Consolidation And Presentation Of Financial Statements [Line Items]                                  
Aggregate principal amount                 $ 51,800,000                
Debt instrument interest rate                 6.50%                
Private Placement and Rights Offering | RLNs                                  
Organization Consolidation And Presentation Of Financial Statements [Line Items]                                  
Aggregate principal amount                 $ 100,000                
Private Placement | June 3 SPA                                  
Organization Consolidation And Presentation Of Financial Statements [Line Items]                                  
Number of warrants to purchase ordinary shares | shares           208,023                      
Warrants to purchase ordinary shares, exercise price | $ / shares           $ 2.1031 $ 1.62                    
Warrants expiry date           Jun. 03, 2025 Dec. 05, 2025                    
Warrants closing date             Jun. 05, 2020                    
Percentage of ordinary shares issued to purchase warrants           7.00%                      
Private Placement | June 30 SPA                                  
Organization Consolidation And Presentation Of Financial Statements [Line Items]                                  
Number of warrants to purchase ordinary shares | shares         236,088                        
Warrants to purchase ordinary shares, exercise price | $ / shares         $ 1.8531         $ 1.42              
Warrants expiry date         Jun. 30, 2025         Jan. 02, 2026              
Warrants closing date                   Jul. 02, 2020              
Percentage of ordinary shares issued to purchase warrants         7.00%                        
Private Placement | Maximum | June 3 SPA                                  
Organization Consolidation And Presentation Of Financial Statements [Line Items]                                  
Number of warrants to purchase ordinary shares | shares             1,485,885                    
Private Placement | Maximum | June 30 SPA                                  
Organization Consolidation And Presentation Of Financial Statements [Line Items]                                  
Number of warrants to purchase ordinary shares | shares                   1,686,343              
Private Placement | 2025 Exchangeable Notes                                  
Organization Consolidation And Presentation Of Financial Statements [Line Items]                                  
Aggregate principal amount                 51,600,000                
Debt instrument price per unit                 1,000                
Private Placement | RLNs                                  
Organization Consolidation And Presentation Of Financial Statements [Line Items]                                  
Aggregate principal amount                 $ 100,000                
Number of debt instruments within each notes | Debtinstrument                 50                
Debt instrument, aggregate potential payment capped value                 $ 160,000                
Debt instrument, aggregate potential payment capped rate                 4,000 times                
Private Placement | Securities                                  
Organization Consolidation And Presentation Of Financial Statements [Line Items]                                  
Debt instrument, shares embedded within each unit, shares | shares                 1,000                
Debt instrument, shares embedded within each unit, value                 $ 1,000                
Private Placement | Securities | Subsequent Event                                  
Organization Consolidation And Presentation Of Financial Statements [Line Items]                                  
Debt instrument, shares embedded within each unit, shares | shares 1,286.1845                                
Debt instrument, shares embedded within each unit, value $ 1,000                                
Rights Offering in Connection with Private Placement                                  
Organization Consolidation And Presentation Of Financial Statements [Line Items]                                  
Maximum subscription units to be accepted | shares                 220                
Rights Offering in Connection with Private Placement | 2025 Exchangeable Notes                                  
Organization Consolidation And Presentation Of Financial Statements [Line Items]                                  
Aggregate principal amount                               $ 200,000  
Debt instrument price per unit                 $ 1,000                
Debt instrument price per unit                 $ 1,000                
Debt instrument, shares embedded within each unit, shares | shares                 1,000                
Debt instrument, shares embedded within each unit, value                 $ 1,000                
Debt instrument, shares embedded within each unit, exchange price | $ / shares                 $ 1.00                
Rights Offering in Connection with Private Placement | 2025 Exchangeable Notes | Subsequent Event                                  
Organization Consolidation And Presentation Of Financial Statements [Line Items]                                  
Debt instrument, shares embedded within each unit, shares | shares 1,286.1845                                
Debt instrument, shares embedded within each unit, value $ 1,000,000                                
Debt instrument, shares embedded within each unit, exchange price | $ / shares $ 0.7775                                
Rights Offering in Connection with Private Placement | RLNs                                  
Organization Consolidation And Presentation Of Financial Statements [Line Items]                                  
Aggregate principal amount                               $ 20,000  
Number of debt instruments within each notes | Debtinstrument                 50                
Debt instrument, aggregate potential payment capped value                 $ 160,000                
Debt instrument, aggregate potential payment capped rate                 4,000 times                
Rights Offering in Connection with Private Placement | RLNs | Minimum                                  
Organization Consolidation And Presentation Of Financial Statements [Line Items]                                  
Debt instrument, percentage of net revenue from domestic sale for potential aggregate payments                 15.00%                
Rights Offering in Connection with Private Placement | RLNs | Maximum                                  
Organization Consolidation And Presentation Of Financial Statements [Line Items]                                  
Debt instrument, percentage of net revenue from domestic sale for potential aggregate payments                 20.00%                
Rights Offering in Connection with Private Placement | Securities                                  
Organization Consolidation And Presentation Of Financial Statements [Line Items]                                  
Proceeds from sales of securities                 $ 45,000,000                
Direct Offering | June 3 SPA                                  
Organization Consolidation And Presentation Of Financial Statements [Line Items]                                  
Ordinary shares, shares issued | shares             2,971,770                    
Ordinary shares, par value | $ / shares             $ 0.01                    
Purchase price per share | $ / shares             $ 1.6825                    
Aggregate gross proceeds from ordinary shares             $ 5,000,000                    
Proceeds from registered direct offerings, net of transaction costs             $ 4,300,000                    
Direct Offering | June 30 SPA                                  
Organization Consolidation And Presentation Of Financial Statements [Line Items]                                  
Ordinary shares, shares issued | shares                   3,372,686              
Ordinary shares, par value | $ / shares                   $ 0.01              
Purchase price per share | $ / shares                   $ 1.4825              
Aggregate gross proceeds from ordinary shares                   $ 5,000,000              
Proceeds from registered direct offerings, net of transaction costs                   $ 4,200,000              
October Offering | Purchase Agreement                                  
Organization Consolidation And Presentation Of Financial Statements [Line Items]                                  
Description of purchase agreement                         In connection with the October Offering, the Company entered into a Securities Purchase Agreement (the Purchase Agreement) on October 22, 2020 with certain institutional investors. The Purchase Agreement contains customary representations and warranties of the Company, termination rights of the parties, and certain indemnification obligations of the Company and ongoing covenants of the Company, including a prohibition on issuance of ordinary shares or securities convertible or exchangeable into ordinary shares by the Company for a period of 45 days after the closing of the October Offering and a prohibition on the Company entering into variable rate transactions for a period of 12 months after the closing of the October Offering, subject to certain exceptions.        
October Offering | Subsequent Event                                  
Organization Consolidation And Presentation Of Financial Statements [Line Items]                                  
Ordinary shares, shares issued | shares     15,511,537                            
Ordinary shares, par value | $ / shares     $ 0.01                            
Aggregate gross proceeds from ordinary shares     $ 17,400,000                            
Proceeds from registered direct offerings, net of transaction costs   $ 60,000 $ 15,300,000                            
Warrants to purchase ordinary shares, exercise price | $ / shares   $ 0.8125                              
Warrants expiry date   Oct. 22, 2025 Oct. 27, 2025                            
Percentage of ordinary shares issued to purchase warrants   7.00%                              
October Offering | Subsequent Event | Pre-Funded Warrants                                  
Organization Consolidation And Presentation Of Financial Statements [Line Items]                                  
Ordinary shares, par value | $ / shares     $ 0.01                            
Purchase price per share | $ / shares     $ 0.01                            
Proceeds from registered direct offerings, net of transaction costs   $ 60,000                              
Number of warrants to purchase ordinary shares | shares   6,284,615 11,411,539                            
Warrants to purchase ordinary shares, exercise price | $ / shares     $ 0.64                            
Percentage of ordinary share at election of purchaser     9.99%                            
October Offering | Subsequent Event | Warrant                                  
Organization Consolidation And Presentation Of Financial Statements [Line Items]                                  
Purchase price per share | $ / shares     $ 0.65                            
Number of warrants to purchase ordinary shares | shares   1,884,615 20,192,307                            
Warrants to purchase ordinary shares, exercise price | $ / shares     $ 0.65                            
Warrants expiry date     Oct. 27, 2025                            
October Offering | Subsequent Event | Purchase Agreement                                  
Organization Consolidation And Presentation Of Financial Statements [Line Items]                                  
Number of warrants to purchase ordinary shares | shares       1,884,615                          
Warrants to purchase ordinary shares, exercise price | $ / shares       $ 0.8125                          
Warrants expiry date       Oct. 22, 2025                          
Percentage of ordinary shares issued to purchase warrants       7.00%                          
October Offering | Minimum | Subsequent Event | Pre-Funded Warrants                                  
Organization Consolidation And Presentation Of Financial Statements [Line Items]                                  
Percentage of outstanding ordinary shares     4.99%