Calculation of Basic and Diluted Net Income (Loss) Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Numerator:
Net income (loss)	$ (2,182)	$ 4,107
Denominator (in thousands):
Basic weighted-average common stock outstanding	22,148	21,398
Effect of stock -based awards		789
Diluted weighted average common stock outstanding	22,148	22,187
Basic net income (loss) per share	$ (0.10)	$ 0.19
Diluted net income (loss) per share	$ (0.10)	$ 0.19