v3.8.0.1

Financial risk management (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest Rate Risk [Member]
Financial risk management [Abstract]
Forecasted increase in benchmark interest rate	0.25%
Forecasted loss on cash flow hedges due to increase in benchmark interest rate	$ (228)	$ (2,563)	$ (1,795)
Forecasted increase in hedging reserves due to increase in benchmark interest rate	$ 37,767	$ 37,290	$ 41,702
Interest Rate Risk [Member] | Euros [Member]
Financial risk management [Abstract]
Maturity date	2030
Interest Rate Risk [Member] | Euros [Member] | Bottom of Range [Member]
Financial risk management [Abstract]
Percentage of notional amount of debt hedged	87.00%
Interest rate	3.20%
Interest Rate Risk [Member] | Euros [Member] | Top of Range [Member]
Financial risk management [Abstract]
Percentage of notional amount of debt hedged	100.00%
Interest rate	4.87%
Interest Rate Risk [Member] | U.S. Dollars [Member]
Financial risk management [Abstract]
Maturity date	2032
Interest Rate Risk [Member] | U.S. Dollars [Member] | Bottom of Range [Member]
Financial risk management [Abstract]
Percentage of notional amount of debt hedged	70.00%
Interest rate	2.32%
Interest Rate Risk [Member] | U.S. Dollars [Member] | Top of Range [Member]
Financial risk management [Abstract]
Percentage of notional amount of debt hedged	100.00%
Interest rate	5.27%
Currency Risk [Member]
Financial risk management [Abstract]
Net Euro exposure percentage for next fiscal year	100.00%
Net Euro exposure percentage for following fiscal period	75.00%

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- References

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- Definition

The forecasted gain (loss) on cash flow hedges attributable to a change in the benchmark interest rate.

+ References

No definition available.

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- Definition

The forecasted increase (decrease) in the benchmark interest rate used to calculate the impact of interest rate derivative positions on the income statement, assuming all other variables remain constant.

+ References

No definition available.

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- Definition

The forecasted increase (decrease) in hedging reserves attributable to a change in the benchmark interest rate.

+ References

No definition available.

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- Definition

Refers to net value exposure percentage for the next fiscal year.

+ References

No definition available.

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Refers to net value exposure percentage in the year following the latest fiscal year.

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The percentage of the notional amount of the entity's debt hedged with interest rate swaps and options.

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- Definition

The interest rate on borrowings. [Refer: Borrowings]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IFRS
-Number 7
-IssueDate 2016-01-13
-Paragraph 7
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The maturity of borrowings. [Refer: Borrowings]

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-Number 7
-IssueDate 2016-01-13
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