Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Condensed Consolidated Statements of Operations and Comprehensive Loss
Collaboration revenue	$ 18,067	$ 5,197
Operating expenses:
Research and development	32,294	24,831
General and administrative	10,206	9,659
Total operating expenses	42,500	34,490
Operating loss	(24,433)	(29,293)
Other income:
Interest income	978	1,145
Other (expense) income	(808)	978
Total other income	170	2,123
Net loss	(24,263)	(27,170)
Other comprehensive income
Net unrealized gain on available-for-sale-securities	525	58
Total other comprehensive income	525	58
Comprehensive loss	$ (23,738)	$ (27,112)
Net loss per share, basic and diluted	$ (0.66)	$ (0.81)
Weighted-average common shares outstanding, basic and diluted	36,963,255	33,353,061