EARNINGS PER SHARE - Weighted Average Number of Common Shares Outstanding (Details) - shares	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings per share [abstract]
Basic (in shares)	58,815,526	59,072,119	58,727,751
Effect of stock options (in shares)	268,649	371,933	473,446
Effect of PSUs (in shares)	0	143,717	1,168,030
Diluted (in shares)	59,084,175	59,587,769	60,369,227

The weighted average number of ordinary shares outstanding plus the weighted average number of ordinary shares that would be issued on the conversion of all the dilutive potential ordinary shares into ordinary shares. [Refer: Ordinary shares [member]; Weighted average [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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The number of dilutive potential ordinary shares that relate to the assumed exercise of the entity's share options.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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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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Diluted Effect Of Other Equity Instruments On Number Of Ordinary Shares

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