Accrued expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Accrued expenses
Accrued savings offers	$ 11,645	$ 16,790
Accrued rebates	5,018	6,109
Accrued customer returns	4,869	5,122
Accrued wholesaler fees	2,991	5,014
Accrued payroll and benefits	3,620	4,485
Other accrued expenses	2,413	2,668
Total accrued expenses	$ 30,556	$ 40,188