Reconciliation of Weighted Average Shares Used in Computation of Loss Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Earnings Per Share Disclosure [Line Items]
Net loss available to common stockholders	$ (16,742)	$ (4,369)	$ (35,058)	$ (21,784)
Shares used in loss per share	21,616	16,402	19,865	16,818
Loss per share	$ (0.77)	$ (0.27)	$ (1.77)	$ (1.30)