Net Loss per Share of Common Stock - Summary of Computation of Basic and Diluted Net Loss Per Share (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Earnings Per Share [Abstract]
Net loss attributable to common stockholders - basic and diluted	$ (13,834)	$ (5,009)	$ (67,419)	$ (12,683)
Weighted-average shares outstanding	24,194,808	250,991	17,137,647	178,023
Less: weighted average shares subject to repurchase		(246)		(246)
Weighted-average shares used to compute basic and diluted net loss per share	24,194,808	250,745	17,137,647	177,777
Basic and diluted net loss per common share	$ (0.57)	$ (19.98)	$ (3.93)	$ (71.34)

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

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This element represents the weighted average total number of shares issued throughout the period including the first (beginning balance outstanding) and last (ending balance outstanding) day of the period before considering any reductions (for instance, shares held in treasury) to arrive at the weighted average number of shares outstanding. Weighted average relates to the portion of time within a reporting period that common shares have been issued and outstanding to the total time in that period. Such concept is used in determining the weighted average number of shares outstanding for purposes of calculating earnings per share (basic).

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