Number of outstanding awards not including in computation diluted earnings per share.

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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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Face amount or stated value per share of common stock.

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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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Nature of business (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Numerator for (loss) earnings per common share calculation:
Net (loss) income	$ (1,054)	$ 682	$ (13,719)	$ 8,608
Denominator for (loss) earnings per common share calculation:
Weighted-average common shares, basic	38,969	40,398	38,982	40,515
Effect of dilutive securities:
Stock options, restricted stock and warrants		527		316
Weighted-average common shares, diluted	38,969	40,925	38,982	40,831
(Loss) earnings per share
Basic (in dollars per share)	$ (0.03)	$ 0.02	$ (0.35)	$ 0.21
Diluted (in dollars per share)	$ (0.03)	$ 0.02	$ (0.35)	$ 0.21
Shares excluded from the computation of diluted income per common share	1,200		1,700
Outstanding awards excluded from computation of diluted earnings per share	300		300
Common Class A
(Loss) earnings per share
Par value of common stock (in dollars per share)	$ 0.0001		$ 0.0001		$ 0.0001
Common Class B
(Loss) earnings per share
Par value of common stock (in dollars per share)	$ 0.0001		$ 0.0001		$ 0.0001