Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Revenue:
Collaboration revenue	$ 15,608	$ 6,832
License and royalty revenue	349
Total revenues	15,957	6,832
Operating expenses:
Research and development	97,109	55,028
General and administrative	34,926	20,284
Cost of license and royalty revenue	17
Change in fair value of contingent consideration	534	1,433
Total operating expenses	132,586	76,745
Loss from operations	(116,629)	(69,913)
Interest income, net	1,388	1,556
Other income (expense), net	115	(355)
Loss before income taxes	(115,126)	(68,712)
Net loss	$ (115,126)	$ (68,712)
Net loss per share - basic and diluted:	$ (2.31)	$ (1.68)
Weighted-average number of common shares used in computing net loss per share - basic and diluted:	49,923	40,836
Other comprehensive loss:
Other comprehensive loss, net of tax expense of $0.0 and $0.0 million for the three months ended March 31, 2018 and 2017, respectively	$ (844)	$ (101)
Total other comprehensive loss	(844)	(101)
Comprehensive loss	$ (115,970)	$ (68,813)

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Amount of increase (decrease) in the value of a contingent consideration liability, including, but not limited to, differences arising upon settlement.

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Amount after tax and reclassification adjustments of other comprehensive income (loss).

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The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use.

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Average number of shares or units issued and outstanding that are used in calculating basic and diluted earnings per share (EPS).

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