Quarterly report pursuant to Section 13 or 15(d)

Debt - Additional Information (Details)

Debt - Additional Information (Details)				3 Months Ended	6 Months Ended
Debt - Additional Information (Details)	Apr. 30, 2020 USD ($)	Jan. 21, 2020 USD ($) Debtinstrument $ / shares shares	Apr. 27, 2018 USD ($) $ / shares shares	Jun. 30, 2020 USD ($) $ / shares shares	Jun. 30, 2020 USD ($) $ / shares shares	Jun. 30, 2019 USD ($)
Debt Instrument [Line Items]
Accretion of debt discounts and deferred financing costs					$ 4,720,000	$ 170,000
Derivative liability for the exchange option, fair value		$ 27,038,000		$ 12,743,000	12,743,000
Private placement transaction costs					$ 2,130,000
Ordinary Shares
Debt Instrument [Line Items]
Number of warrants to purchase ordinary shares \| shares			19,890	19,890	19,890
Loan and Security Agreement \| Silicon Valley Bank (SVB)
Debt Instrument [Line Items]
Loan and security agreement entered date					Apr. 27, 2018
Funded amount under agreement			$ 15,000,000
Remaining borrowing facility available date			Oct. 31, 2019
Maximum amount available under agreement			$ 30,000,000
Non-utilization fee percentage of undrawn principal amount			1.50%
Frequency of amortization payments					Monthly
Date of first required payment of initial draw			Nov. 01, 2019
Minimum fixed interest rate per annum			8.31%
Final interest rate payment on outstanding principal			4.20%
Principal and interest payment, maturity date			Mar. 01, 2022
Final payment fee			$ 630,000
Prepayment fee in first year			4.00%
Prepayment fee in second year			3.00%
Prepayment fee thereafter			2.00%
Principal payment during the period			$ 3,103,000
Effective annual interest rate on outstanding debt				10.35%	10.35%
Interest expense					$ 776,000	710,000
Accretion of debt discounts and deferred financing costs					$ 229,000	$ 170,000
Loan and Security Agreement \| Silicon Valley Bank (SVB) \| Wall Street Journal Prime Rate
Debt Instrument [Line Items]
Basis spread on interest rate			3.89%
Loan and Security Agreement \| Silicon Valley Bank (SVB) \| Maximum
Debt Instrument [Line Items]
Maximum amount available under second draw			$ 15,000,000
Silicon Valley Bank and Life Sciences Fund II LLC
Debt Instrument [Line Items]
Percentage of purchase additional ordinary shares equal to term loan divided by applicable exercise price			2.50%
Silicon Valley Bank and Life Sciences Fund II LLC \| Series B Convertible Preferred Shares
Debt Instrument [Line Items]
Number of warrants to purchase ordinary shares \| shares			19,890	19,890	19,890
Warrants to purchase ordinary shares, exercise price \| $ / shares			$ 18.85	$ 18.85	$ 18.85
2025 Exchangeable Notes
Debt Instrument [Line Items]
Interest expense				$ 827,000	$ 1,479,000
Accretion of debt discounts and deferred financing costs				$ 2,013,000	$ 3,602,000
Debt instrument interest rate				6.50%	6.50%
Debt instrument, shares embedded within each unit, shares \| shares					1,000
Debt instrument, shares embedded within each unit, exchange price \| $ / shares					$ 1
Debt instrument, payment terms					The Company will be required to pay the holder of the Exchangeable Notes the greater of three times the outstanding principal amount of such Exchangeable Note and the consideration that would be received by the holder of such Exchangeable Note in connection with such Fundamental Change if the holder had exchanged its note for ordinary shares immediately prior to the consummation of such Fundamental Change, plus any accrued and unpaid interest.
Derivative liability for the exchange option, fair value		27,038,000
Private placement transaction costs		2,130,000
Private placement transaction costs, capitalized		2,135,000
2025 Exchangeable Notes \| Private Placement
Debt Instrument [Line Items]
Aggregate principal amount		$ 51,600,000
Debt instrument interest rate		6.50%
Debt instrument price per unit		$ 1,000
RLNs \| Private Placement
Debt Instrument [Line Items]
Aggregate principal amount		$ 100,000
Number of debt instruments within each notes \| Debtinstrument		50
Securities \| Private Placement
Debt Instrument [Line Items]
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
Paycheck Protection Program
Debt Instrument [Line Items]
Interest expense				$ 1,000	$ 1,000
Paycheck Protection Program \| Silicon Valley Bank (SVB) \| Iterum Therapeutics US Limited
Debt Instrument [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 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 expects to incur qualifying payroll costs and other operating expenses in the 24 weeks from April 30, 2020, such that the Company may be able to request forgiveness for a portion of the loan from the Lender