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
	Mar. 31, 2017	Mar. 31, 2016
Earnings Per Share Disclosure [Line Items]
Net loss available to common stockholders	$ (18,316)	$ (17,415)
Shares used in loss per share	18,104	17,218
Loss per share	$ (1.01)	$ (1.01)