Accounts payable, accrued liabilities and long-term liabilities - Summary (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Payables and Accruals [Abstract]
Accounts payable	$ 10,507	$ 8,531
Accrued Clinical Expense	11,945	10,154
Accrued development and other expense	1,814	1,243
Accrued compensation and benefits	3,419	5,847
Total accounts payable and accrued liabilities	27,685	25,775
Long-term liabilities	$ 761	732
Deferred revenue		100
Other liabilities		$ 600