Development Derivative Liability - Roll Forward (Details) - Derivative - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Initial payment, net of common stock warrants		$ 2,100
Funding during the period		21,700
Change in fair value	$ 4,300	8,400
SFJ Agreement | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance		0
Initial payment, net of common stock warrants		2,075
Funding during the period		21,714
Change in fair value		8,435
Ending balance	$ 32,224	$ 32,224