Earnings Per Share Attributable to Stockholders (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Net income attributable to:
Basic	$ 18,164		$ 17,138
Diluted	$ 18,164	$ 17,138
Weighted average number of shares outstanding:
Basic	108,765,489	107,355,381	107,355,381
Diluted	110,044,213	108,643,897
Per Share Amount
Basic	$ 0.17	$ 0.16	$ 0.16
Diluted	$ 0.17	$ 0.16
Share Units [Member]
Weighted average number of shares outstanding:
Effect of dilutive securities:	486,626	358,087
Stock Options [Member]
Weighted average number of shares outstanding:
Effect of dilutive securities:	792,098	930,429

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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