Earnings (Loss) per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Numerator
Net income (loss)	$ 56,076	$ (44,922)
Denominator
Weighted-average shares outstanding, basic (in shares)	68,380	68,222
Effect of dilutive stock awards (in shares)	136	0
Adjusted weighted-average shares outstanding, diluted (in shares)	68,516	68,222
Earnings (loss) per share
Basic earnings per common share (in dollars per share)	$ 0.82	$ (0.66)
Diluted earnings per common share (in dollars per share)	$ 0.82	$ (0.66)
Anti-dilutive weighted-average shares (in shares)	159	324

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

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