Financial risk management (Details Textual)	12 Months Ended
Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Financial risk management [Line Items]
Closing foreign exchange rate \| Pure	694.77	614.75
Percentage of Financial Liabilities Maturing in Next 12 Months	5.00%
Undrawn borrowing facilities	$ 481,000,000
Finance income (cost)	0.06
Derivatives [member]
Financial risk management [Line Items]
Financial assets, at fair value	3,900,000	$ 5,000,000
Adjustments for unrealised foreign exchange losses (gains)	$ 400,000,000

Adjustments for unrealised foreign exchange losses (gains) to reconcile profit (loss) to net cash flow from (used in) operating activities. [Refer: Profit (loss)]

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The spot exchange rate at the end of the reporting period. Exchange rate is the ratio of exchange for two currencies. Spot exchange rate is the exchange rate for immediate delivery.

+ References

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The amount of income or cost associated with interest and other financing activities of the entity.

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The fair value of financial assets. [Refer: At fair value [member]; Financial assets]

+ References

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The amount of undrawn borrowing facilities that may be available for future operating activities and to settle capital commitments. [Refer: Capital commitments]

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The percentage of financial liabilities that are maturing in next 12 months.

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