Other current liabilities - Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Other Liabilities Disclosure [Abstract]
Reserves	$ 13,617	$ 11,659
Accrued foreign taxes	13,227	6,053
Accrued losses on contracts	11,455	11,352
Other	6,738	1,829
Other current liabilities	$ 45,037	$ 30,893