Earnings (Loss) per Share - Schedule of Earnings (Loss) 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
Earnings Per Share [Abstract]
Basic earnings (loss) per share, Net Income (Loss)	$ 55,034	$ 65,655	$ (181,945)	$ (626)
Diluted earnings (loss) per share, Net Income (Loss)	$ 55,034	$ 65,655	$ (181,945)	$ (626)
Basic earnings (loss) per share, Shares	86,012	85,290	85,712	84,787
Effect of dilutive incentive-based awards, Shares	272	157
Diluted earnings (loss) per share, Shares	86,284	85,447	85,712	84,787
Basic earnings (loss) per share, Per Share Amount	$ 0.64	$ 0.77	$ (2.12)	$ (0.01)
Diluted earnings (loss) per share, Per Share Amount	$ 0.64	$ 0.77	$ (2.12)	$ (0.01)

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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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Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities; of income (loss) available to common shareholders.

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Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities, and addition from assumption of issuance of common shares for dilutive potential common shares; of income (loss) available to common shareholders.

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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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