Revenue from Contracts with Customers - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2020	Dec. 31, 2019
Disaggregation Of Revenue [Line Items]
Revenues	$ 247,529	$ 279,872	$ 493,749	$ 502,974
Contract asset, current	9,240		$ 9,240			$ 8,386
Consideration expects to receive			3 years
Other Noncurrent Assets
Disaggregation Of Revenue [Line Items]
Contract asset, non-current	5,000		$ 5,000
Minimum
Disaggregation Of Revenue [Line Items]
Manufacturing Process period			10 days
Maximum
Disaggregation Of Revenue [Line Items]
Manufacturing Process period			56 days
Research and development revenue
Disaggregation Of Revenue [Line Items]
Revenues	609	14,340	$ 852	29,046
Research and development revenue | Biogen
Disaggregation Of Revenue [Line Items]
Revenues	$ 100	$ 13,600	$ 200	$ 27,400
Research and development revenue | Biogen | Forecast
Disaggregation Of Revenue [Line Items]
Additional revenue expected					$ 300