Accounts payable and accrued expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Payables and Accruals [Abstract]
Employee compensation, benefits, and related accruals	$ 12,915	$ 13,649
Consulting and contracted research	9,536	11,505
Professional fees	1,873	1,237
Sales allowance and other costs	29,190	13,245
Accounts payable	5,994	6,298
Other	4,546	2,825
Accounts payable and accrued expenses	$ 64,054	$ 48,759