Immaterial Restatement Of Prior Period Financial Statements For Stock-Based Compensation - Summary of Revisions to the Consolidated Statements of Comprehensive Loss (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net loss	$ 13,744	$ (20,852)	$ (2,074)	$ (44,398)
Total comprehensive loss		(23,011)		(44,598)
Previously Reported [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net loss		(20,468)		(43,435)
Total comprehensive loss		$ (22,627)		$ (43,635)

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

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