Commitments and Contingencies - Narrative (Details) ft² in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Aug. 31, 2021 USD ($) ft²	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)
Loss Contingencies [Line Items]
Sublease income		$ 1,000,000.0	$ 900,000	$ 2,900,000	$ 2,800,000
DMSA
Loss Contingencies [Line Items]
Purchase order executed		42,000,000		42,000,000		$ 33,000,000
Non-refundable purchase commitments		27,600,000		27,600,000		$ 27,100,000
Costs incurred		5,800,000	1,400,000	14,200,000	6,200,000
Payments for development and manufacturing services		4,000,000	$ 800,000	10,400,000	$ 6,000,000
Operating Lease, 8 Year Lease Agreement | Building
Loss Contingencies [Line Items]
Lease not yet commenced, area under lease | ft²	50
Lease not yet commenced, period	8 years 4 months 24 days
Lease not yet commenced, undiscounted lease payments	$ 12,500,000
Lease not yet commenced, lease liability		0		0
Lease not yet commenced, ROU asset		0		0
Lease not yet commenced, operating lease expense		$ 0		$ 0