SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Calculation of Basic and Diluted Net Income Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disclosure Calculation Of Basic And Diluted Net Income Per Share [Abstract]
Net loss	$ (1,986)	$ (6,029)	$ (16,779)	$ (28,960)
Weighted average shares – basic	(49,833)	(49,771)	(49,814)	(48,627)
Effect of dilutive potential common shares	0	0	0	0
Weighted average shares – diluted	49,833	49,771	49,814	48,627
Basic net loss per share (in dollars per share)	$ (0.04)	$ (0.12)	$ (0.34)	$ (0.60)
Diluted net loss per share (in dollars per share)	$ (0.04)	$ (0.12)	$ (0.34)	$ (0.60)
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	3,688	2,841	3,688	2,841