Significant Accounting Policies - Net Income (Loss) Per Share (Details) - shares shares in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Schedule of reconciliation of shares used to calculate basic and diluted earnings per share
Weighted average shares outstanding used to compute basic earnings per share	21,777	10,879	21,638	10,812
Incremental shares issuable upon the assumed exercise of stock options	58	51	75	48
Unvested restricted stock and restricted stock units	274	450	366	486
Shares used to compute diluted earnings per share	22,109	11,380	22,079	11,346

Number of additional shares included in diluted EPS for potentially dilutive effect of nonvested equity-based payment award containing forfeitable rights to dividends or dividend equivalents, whether paid or unpaid.

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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 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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