Earnings per share attributable to stockholders (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Net income attributable to:
Basic	$ 22,809	$ 18,164
Diluted	$ 22,809	$ 18,164
Weighted average number of shares outstanding:
Basic	109,248,880	108,765,489
Diluted	110,482,837	110,044,213
Per Share Amount
Basic	$ 0.21	$ 0.17
Diluted	$ 0.21	$ 0.17
Share Units [Member]
Weighted average number of shares outstanding:
Effect of dilutive securities:	586,074	486,626
Stock Options [Member]
Weighted average number of shares outstanding:
Effect of dilutive securities:	647,883	792,098

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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