Annual report pursuant to Section 13 and 15(d)

Debt - Additional Information (Details)

Debt - Additional Information (Details)						1 Months Ended		12 Months Ended
Debt - Additional Information (Details)	Nov. 02, 2020 USD ($) $ / shares shares	Sep. 08, 2020 USD ($) Debtinstrument $ / shares shares	Apr. 30, 2020 USD ($)	Jan. 21, 2020 USD ($) Debtinstrument $ / shares shares	Apr. 27, 2018 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares	Nov. 30, 2020 USD ($)	Dec. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Debt Instrument [Line Items]
Accretion of debt discounts and deferred financing costs								$ 10,929,000	$ 362,000	$ 360,000
Fair value of derivative liability				$ 27,038,000
Fair value of derivative liability related to rights offering				82,000
Financing transaction costs								$ 2,848,000
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					$ 6,207,000
Effective annual interest rate on outstanding debt						12.51%		12.51%
Interest expense								$ 1,355,000	1,761,000
Accretion of debt discounts and deferred financing costs								$ 404,000	$ 362,000
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								$ 3,180,000
Accretion of debt discounts and deferred financing costs								7,764,000
Aggregate principal amount						$ 9,891,000		$ 9,891,000
Debt instrument, payment terms								The Company will be required to pay the holders of the Exchangeable Notes the greater of three times the outstanding principal amount of such Exchangeable Notes and the consideration that would be received by the holders of such Exchangeable Notes in connection with such Fundamental Change if the holders had exchanged their notes for ordinary shares immediately prior to the consummation of such Fundamental Change, plus any accrued and unpaid interest.
Financing transaction costs								$ 2,848,000
Financing transaction costs, capitalized				2,814,000
2025 Exchangeable Notes \| Private Placement
Debt Instrument [Line Items]
Aggregate principal amount		$ 200,000		$ 51,600,000
Debt instrument interest rate		6.50%		6.50%
Debt instrument price per unit		$ 1,000		$ 1,000
Fair value of derivative liability				27,038,000
2025 Exchangeable Notes \| Rights Offering
Debt Instrument [Line Items]
Fair value of derivative liability related to rights offering		82,000
RLNs \| Private Placement
Debt Instrument [Line Items]
Aggregate principal amount		$ 20,000		$ 100,000
Number of debt instruments within each notes \| Debtinstrument		50		50
Securities \| Private Placement
Debt Instrument [Line Items]
Debt instrument price per unit		$ 1,000		$ 1,000
Debt instrument, shares embedded within each unit, shares \| shares	1,286.1845	1,000		1,000
Debt instrument, shares embedded within each unit, value	$ 1,000	$ 1,000		$ 1,000
Debt instrument, shares embedded within each unit, exchange price \| $ / shares	$ 0.7775	$ 1.00		$ 1.00
Paycheck Protection Program \| Silicon Valley Bank (SVB) \| Iterum Therapeutics US Limited
Debt Instrument [Line Items]
Interest expense			$ 1,000
Aggregate principal amount			$ 744,000
Debt instrument interest rate			1.00%
Debt instrument maturity period			2 years
Debt instrument, description			Under the terms of the agreement, there shall be no payments due by the Company until 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 by the maturity date					Under the terms of the agreement, there shall be no payments due by the Company until after 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 by the maturity date.
Debt instrument, forgiveness loan							$ 340,000
Debt instrument, remaining amount amortized						404,000		$ 404,000
Debt Instrument, equal monthly repayments						$ 26,000		$ 26,000