Accounting Policies - Computation of Numerators and Denominators Used in Basic and Diluted Income (Loss) per Share Amounts (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Numerator:
Net income (loss)	$ 1,513	$ (7,246)	$ 5,433	$ (9,434)
Weighted average shares outstanding:
Denominator for basic income (loss) per share—weighted average shares	65,580	50,374	64,614	50,255
Effect of dilutive securities, stock options and RSUs	7,811		8,267
Denominator for dilutive income (loss) per share	73,391	50,374	72,881	50,255
Net income (loss) per share attributable to common stockholders, basic	$ 0.02	$ (0.14)	$ 0.08	$ (0.19)
Net income (loss) per share attributable to common stockholders, diluted	$ 0.02	$ (0.14)	$ 0.07	$ (0.19)