Quarterly report pursuant to Section 13 or 15(d)

Debt - Additional Information (Details)

Debt - Additional Information (Details)			3 Months Ended
Debt - Additional Information (Details)	Jan. 21, 2020 USD ($) Debtinstrument $ / shares shares	Apr. 27, 2018 USD ($) $ / shares shares	Mar. 31, 2020 USD ($) $ / shares shares	Mar. 31, 2019 USD ($)
Debt Instrument [Line Items]
Accretion of debt discounts and deferred financing costs			$ 1,614,000	$ 98,000
Derivative liability for the exchange option, fair value	$ 27,038,000		25,359,000
Private placement transaction costs			$ 2,130,000
Ordinary Shares
Debt Instrument [Line Items]
Number of warrants to purchase preferred shares \| shares		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		$ 1,552,000
Effective annual interest rate on outstanding debt			9.78%
Interest expense			$ 410,000	448,000
Accretion of debt discounts and deferred financing costs			116,000	$ 98,000
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 preferred shares \| shares		19,890
Warrants to purchase preferred shares, exercise price \| $ / shares		$ 18.85
2025 Exchangeable Notes
Debt Instrument [Line Items]
Interest expense			652,000
Accretion of debt discounts and deferred financing costs			$ 1,589,000
Debt instrument interest rate			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.
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