Other Assets and Liabilities - Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Accrued Expenses
Accrued compensation	$ 1,724	$ 3,944
Accrued social charges	192	592
Accrued restructuring (see Note 14)	1,705	2,949
Customer allowances	6,200	6,470
Accrued contract research organization charges	1,802	2,098
Accrued contract manufacturing organization costs	426	735
Other	2,809	3,022
Total	$ 14,858	$ 19,810