Stockholders' Equity - Schedule of Stock Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock based compensation, Total expensed	$ 3,188	$ 5,192	$ 7,435	$ 10,023
Property and equipment	7	31	21	53
Total stock based compensation	3,195	5,223	7,456	10,076
Marketing and Selling [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock based compensation, Total expensed	2,152	2,563	3,886	4,893
Research and Development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock based compensation, Total expensed	893	1,078	1,881	2,096
General and Administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock based compensation, Total expensed	1,545	$ 1,551	3,070	$ 3,034
Restructuring Charges [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock based compensation, Total expensed	$ 1,402		$ 1,402

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.

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

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

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