Development Derivative Liability - Roll Forward (Details) - Derivative $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($)
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	600
Change in fair value	500
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	557
Change in fair value	454
Ending balance	$ 3,086