Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenue
Collaborations, licenses, milestones, and royalties	$ 32,385	$ 111,939
Operating expenses
Research and development	33,943	28,183
General and administrative	7,219	5,512
Total operating expenses	41,162	33,695
Income (loss) from operations	(8,777)	78,244
Other income (expenses)
Interest income, net	3,039	2,886
Other expense, net	(2,336)	(185)
Total other income, net	703	2,701
Net income (loss) before income tax expense	(8,074)	80,945
Income tax expense		900
Net income (loss)	(8,074)	80,045
Other comprehensive income (loss)
Net unrealized gain (loss) on marketable securities	(105)	1,316
Comprehensive income (loss)	$ (8,179)	$ 81,361
Net income (loss) per share attributable to common stockholders:
Basic net income (loss) (in dollars per share)	$ (0.14)	$ 1.42
Diluted net income (loss) (in dollars per share)	$ (0.14)	$ 1.38
Weighted average shares used to compute net income (loss) per share attributable to common stockholders:
Basic (in shares)	56,946,714	56,302,967
Diluted (in shares)	56,946,714	58,009,878