Accrued Expenses (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Accrued Liabilities, Current [Abstract]
Accrued compensation and related liabilities	$ 16,969	$ 8,941
Accrued contract payables, current	52,811	15,706
Accrued cash settled stock-based compensation	7,127	3,282
Other accrued expenses	13,788	10,804
Total accrued expenses	$ 90,695	$ 38,733