Accrued expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Accrued Expenses
Accrued payroll and compensation related costs	$ 3,896	$ 2,518
Accrued invoices	2,444	3,500
Accrued sales and other taxes	1,490	706
Accrued litigation	1,077	1,143
Accrued other	945	883
Total	$ 9,852	$ 8,750