CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues:
Collaboration and license	$ 2,136
Product sales	476	$ 133
Total revenues	2,612	133
Operating expenses:
Cost of sales	1
Research and development	231,644	183,204	$ 114,737
Selling, general and administrative	99,909	64,936	33,001
Total operating expenses	331,554	248,140	147,738
Loss from operations	(328,942)	(248,007)	(147,738)
Interest income	4,074	3,789	2,320
Other income (expense)	6,530	(1,621)	(200)
Loss before income taxes	(318,338)	(245,839)	(145,618)
Benefit from (provision for) income taxes	16,199	(35)
Net loss	$ (302,139)	$ (245,874)	$ (145,618)
Net loss per share, basic and diluted	$ (7.12)	$ (6.21)	$ (3.96)
Shares used in computing net loss per share, basic and diluted	42,453,135	39,586,908	36,782,603

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Total costs related to goods produced and sold during the reporting period.

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The amount of net income or loss for the period per each share in instances when basic and diluted earnings per share are the same amount and reported as a single line item on the face of the financial statements. Basic earnings per share is the amount of net income or loss for the period per each share of common stock or unit outstanding during the reporting period. Diluted earnings per share includes the amount of net income or loss for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount before accretion (amortization) of purchase discount (premium) of interest income on nonoperating securities.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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Generally recurring costs associated with normal operations except for the portion of these expenses which can be clearly related to production and included in cost of sales or services. Includes selling, general and administrative expense.

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The net result for the period of deducting operating expenses from operating revenues.

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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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Aggregate revenue during the period from the sale of goods in the normal course of business, after deducting returns, allowances and discounts.

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Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

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The aggregate total costs related to selling a firm's product and services, as well as all other general and administrative expenses. Direct selling expenses (for example, credit, warranty, and advertising) are expenses that can be directly linked to the sale of specific products. Indirect selling expenses are expenses that cannot be directly linked to the sale of specific products, for example telephone expenses, Internet, and postal charges. General and administrative expenses include salaries of non-sales personnel, rent, utilities, communication, etc.

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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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