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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Tangible Assets (Details)	12 Months Ended
	Dec. 31, 2019
Preparation plants, processing facilities and mineral rights | Minimum
Property, Plant and Equipment
Estimated useful life	1 year
Preparation plants, processing facilities and mineral rights | Maximum
Property, Plant and Equipment
Estimated useful life	28 years
Other plant and equipment and mining equipment | Minimum
Property, Plant and Equipment
Estimated useful life	1 year
Other plant and equipment and mining equipment | Maximum
Property, Plant and Equipment
Estimated useful life	28 years
Buildings, office equipment and improvements | Minimum
Property, Plant and Equipment
Estimated useful life	1 year
Buildings, office equipment and improvements | Maximum
Property, Plant and Equipment
Estimated useful life	25 years

X

- Definition

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

+ References

No definition available.

+ Details

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X

- Definition

Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

+ Details

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- Details

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- Details

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- Details

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- Details

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- Details

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