Stock-Based Compensation - Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Stock-based compensation expense
Stock-based compensation expense	$ 25,132	$ 25,016	$ 80,297	$ 66,925
Capitalized stock-based compensation costs	(374)		(1,002)
Total stock-based compensation expense	24,758	25,016	79,295	66,925
Research and development
Stock-based compensation expense
Stock-based compensation expense	7,392	8,545	23,635	23,532
Selling, general and administrative
Stock-based compensation expense
Stock-based compensation expense	$ 17,740	$ 16,471	56,662	43,393
Employee stock purchase plan
Stock-based compensation expense
Total stock-based compensation expense			$ 1,400	$ 1,200

Represents the expense capitalized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

No definition available.

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Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
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-Section 50
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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Amount of capitalized and expensed compensation cost from equity-based compensation arrangements.

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