Derivative financial instruments - Gold forwards narrative (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Disclosure of detailed information about financial instruments [line items]
Losses on change in fair value of derivatives	$ (1,580)	$ (412)
Gold Forward Contracts
Disclosure of detailed information about financial instruments [line items]
Unrealized gains on change in fair value of derivatives		5,000
Losses on change in fair value of derivatives		$ 5,000

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

No definition available.

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- Definition

The gains (losses) resulting from change in the fair value of derivatives recognised in profit or loss. [Refer: Derivatives [member]]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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The gains (losses) recognised in profit or loss for liabilities measured at fair value that are attributable to the change in unrealised gains or losses relating to those liabilities held at the end of the reporting period. [Refer: At fair value [member]]

+ References

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