Earnings per share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings (losses) attributable to owners of the parent	$ 427,697	$ 278,290	$ 220,356
Number of common shares in circulation	263,196,524	263,196,524	263,196,524
Basic earnings per share (US$ per share)	$ 1.6250	$ 1.0573	$ 0.84

The amount of profit (loss) attributable to ordinary equity holders of the parent entity (the numerator) divided by the weighted average number of ordinary shares outstanding during the period (the denominator).

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The profit (loss) attributable to owners of the parent. [Refer: Profit (loss)]

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The number of ordinary shares outstanding at the beginning of the period, adjusted by the number of ordinary shares bought back or issued during the period multiplied by a time-weighting factor.

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