Computation of Basic and Diluted Net Loss per Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Numerator:
Net loss	$ (12,588)	$ (12,240)
Denominator:
Weighted average shares used to compute basic and diluted net loss per share	31,610	30,574
Basic and diluted net loss per share	$ (0.40)	$ (0.40)