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Commitments and Contingencies - Schedule of Expense under JHU Agreement (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Loss Contingencies [Line Items]
Total JHU Agreement expense	$ 29,832	$ 37,502
JHU
Loss Contingencies [Line Items]
Total JHU Agreement expense	203	395
Research and Development | JHU
Loss Contingencies [Line Items]
Total JHU Agreement expense	38	194
General and Administrative | JHU
Loss Contingencies [Line Items]
Total JHU Agreement expense	$ 165	$ 201

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