Accounts payable and accrued liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Payables and Accruals [Abstract]
Other liability	$ 693
Accounts payable	4,731	$ 4,344
Accrued expenses	9,058	6,279
Accrued compensation and benefits	1,972	3,021
Total accounts payable and accrued liabilities	15,761	13,644
Deferred revenue	300
Other Liabilities, Noncurrent	$ 400	$ 314