Accounts payable and accrued liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Payables and Accruals [Abstract]
Accounts payable	$ 1,813	$ 1,655
Accrued expenses	3,568	2,327
Accrued compensation and benefits	1,702	1,414
Current portion of deferred rent	13	0
Total accounts payable and accrued liabilities	$ 7,096	$ 5,396