Accounts payable, accrued liabilities and long-term liabilities - Summary (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Payables and Accruals [Abstract]
Accounts payable	$ 12,568	$ 8,531
Accrued clinical expense	14,687	10,154
Accrued development and other expense	2,613	1,243
Accrued compensation and benefits	4,821	5,847
Total accounts payable and accrued liabilities	34,689	25,775
Long-term liabilities	$ 873	732
Deferred revenue		100
Other liabilities		$ 600