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		6 Months Ended		67 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014
Earnings Per Share [Abstract]
Net loss attributable to common stockholders - basic and diluted	$ (8,600)	$ (3,655)	$ (53,585)	$ (7,674)	$ (107,331)
Weighted-average shares outstanding	24,194,808	148,082	13,550,582	140,934
Less: weighted-average shares subject to repurchase		(369)		(369)
Weighted-average shares used to compute basic and diluted net loss per share	24,194,808	147,713	13,550,582	140,565
Basic and diluted net loss per common share	$ (0.36)	$ (24.74)	$ (3.95)	$ (54.59)