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, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Earning per share reconciliation
Net (loss)/income	$ (1,812)	$ 3,301	$ 36,615	$ 18,237
Weighted-average common shares outstanding	77,691	76,278	77,258	76,323
(Loss)/earnings per share, basic	$ (0.03)	$ 0.04	$ 0.47	$ 0.24
Net (loss)/income	$ (1,812)	$ 3,301	$ 36,615	$ 18,237
Effect of assumed exercise of stock options and RSUs		3,270	5,459	3,078
Weighted-average common shares outstanding, assuming dilution	77,691	79,548	82,717	79,401
(Loss)/earnings per share, diluted	$ (0.03)	$ 0.04	$ 0.44	$ 0.23
Outstanding stock options and RSUs excluded as impact would be anti-dilutive	7,232	296	219	368
Stock Options
Earning per share reconciliation
Weighted-average effect of dilutive securities		1,933	3,519	1,851
RSUs
Earning per share reconciliation
Weighted-average effect of dilutive securities		1,337	1,940	1,227

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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The sum of dilutive potential common shares or units used in the calculation of the diluted per-share or per-unit computation.

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The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

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