Summary of Basic and Diluted Earnings Per Share (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
Earning per share reconciliation
Net (loss)/income	[1]	$ (10,409)	$ 3,702	$ 1,791	$ 56,665
Weighted-average common shares outstanding	[1]	78,635	77,313	78,436	77,039
(Loss)/earnings per share, basic	[1]	$ (0.13)	$ 0.05	$ 0.02	$ 0.74
Net (loss)/income	[1]	$ (10,409)	$ 3,702	$ 1,791	$ 56,665
Effect of dilutive securities			5,632	4,811	5,373
Weighted-average common shares outstanding, assuming dilution	[1]	78,635	82,945	83,247	82,412
(Loss)/earnings per share, diluted	[1]	$ (0.13)	$ 0.04	$ 0.02	$ 0.69
Outstanding anti-dilutive stock options and RSUs	[2]	6,500	237	242	276
Stock Options
Earning per share reconciliation
Weighted-average effect of dilutive securities			3,694	3,132	3,439
RSUs
Earning per share reconciliation
Weighted-average effect of dilutive securities			1,938	1,679	1,934

[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.