Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Revenue
Collaborations, licenses and milestones	$ 13,340	$ 66,007	$ 17,681	$ 73,259
Operating expenses
Research and development	16,919	14,408	31,967	24,443
General and administrative	4,091	3,043	8,903	6,993
Total operating expenses	21,010	17,451	40,870	31,436
Income (loss) from operations	(7,670)	48,556	(23,189)	41,823
Other income (expenses)
Interest income	1,038	368	2,095	726
Interest expense	(3)	(10)	(5)	(37)
Other income	30		30	4
Total other income, net	1,065	358	2,120	693
Income (loss) before income tax	(6,605)	48,914	(21,069)	42,516
Income tax expense	280	1,749	450	1,749
Net income (loss)	(6,885)	47,165	(21,519)	40,767
Other comprehensive income (loss)
Net unrealized gain (loss) on marketable securities	(44)	113	201	732
Comprehensive income (loss)	$ (6,929)	$ 47,278	$ (21,318)	$ 41,499
Net income (loss) per share attributable to common shareholders:
Basic net income (loss) (in dollars per share)	$ (0.15)	$ 1.16	$ (0.46)	$ 1.00
Diluted net income (loss) (in dollars per share)	$ (0.15)	$ 1.13	$ (0.46)	$ 0.98
Weighted average shares used to compute net income (loss) per share attributable to common stockholders:
Basic (in shares)	46,767,759	40,800,586	46,683,744	40,703,688
Diluted (in shares)	46,767,759	41,738,460	46,683,744	41,701,262