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		64 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014
Earnings Per Share [Abstract]
Net loss attributable to common stockholders - basic and diluted	$ (44,985)	$ (4,019)	$ (98,731)
Weighted-average shares outstanding	2,788,087	133,707
Less: weighted average shares subject to repurchase		(738)
Weighted average shares used to compute basic and diluted net loss per share	2,788,087	132,969
Basic and diluted net loss per common share	$ (16.13)	$ (30.23)