Earnings Per Share - Reconciliation of the Numerator and Denominator of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Numerator [Abstract]
Net income	$ 4,214	$ 21,336
Denominator [Abstract]
Shares used for basic income per share	42,745	39,783
Effect of dilutive stock options and restricted stock units outstanding [Abstract]
Shares used for diluted income per share	43,183	43,589
Earnings per share: [Abstract]
Basic	$ 0.10	$ 0.54
Diluted	$ 0.10	$ 0.49
Non-Qualified Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Dilutive securities outstanding not included in the computation of earnings (loss) per share because their effect is anti-dilutive (in shares)	80
Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Dilutive securities outstanding not included in the computation of earnings (loss) per share because their effect is anti-dilutive (in shares)	56	14
Restricted Stock Awards
Effect of dilutive stock options and restricted stock units outstanding [Abstract]
Effect of dilutive stock options and restricted stock units outstanding (in shares)	16
Non-Qualified Stock Options
Effect of dilutive stock options and restricted stock units outstanding [Abstract]
Effect of dilutive stock options and restricted stock units outstanding (in shares)	127	312
Restricted Stock Units
Effect of dilutive stock options and restricted stock units outstanding [Abstract]
Effect of dilutive stock options and restricted stock units outstanding (in shares)	292	405
Performance Stock Units
Effect of dilutive stock options and restricted stock units outstanding [Abstract]
Effect of dilutive stock options and restricted stock units outstanding (in shares)	3
Market Stock Units
Effect of dilutive stock options and restricted stock units outstanding [Abstract]
Effect of dilutive stock options and restricted stock units outstanding (in shares)		533
Warrants Related to Cash Convertible Notes
Effect of dilutive stock options and restricted stock units outstanding [Abstract]
Effect of dilutive stock options and restricted stock units outstanding (in shares)		2,556

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 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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