Summary of Basic and Diluted Earnings 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
Earning per share reconciliation
Net (loss) income	[1]	$ (7,587)	$ 1,288	$ (5,796)	$ 57,953
Weighted-average common shares outstanding	[1]	78,700	77,691	78,525	77,258
(Loss) earnings per share, basic	[1]	$ (0.10)	$ 0.01	$ (0.07)	$ 0.75
Net (loss) income	[1]	$ (7,587)	$ 1,288	$ (5,796)	$ 57,953
Effect of dilutive securities			5,632		5,459
Weighted-average common shares outstanding, assuming dilution	[1]	78,700	83,323	78,525	82,717
(Loss) earnings per share, diluted	[1]	$ (0.10)	$ 0.01	$ (0.07)	$ 0.70
Outstanding anti-dilutive stock options and RSUs	[2]	6,119	105	6,380	219
Stock Options
Earning per share reconciliation
Weighted-average effect of dilutive securities			3,681		3,519
RSUs
Earning per share reconciliation
Weighted-average effect of dilutive securities			1,951		1,940

[1] On January 1, 2018, the Company adopted the ASC 606 revenue recognition standard and has adjusted prior periods to conform. See Note 2. "New Accounting Pronouncements" for additional information.

[2] Certain outstanding stock options and RSUs were excluded from the computation of diluted earnings per share because they were anti-dilutive in the period presented. These awards may be dilutive in the future.