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Goodwill - Key assumptions used in the determination of recoverable value (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Disclosure of significant unobservable inputs used in fair value measurement of assets [abstract]
Period of projections	5 years
Electrometallurgy United States Segment
Disclosure of significant unobservable inputs used in fair value measurement of assets [abstract]
Weighted Average Cost of Capital	11.00%	10.50%
Long-Term Growth Rate	2.00%	1.50%
Normalized Tax Rate	22.00%	27.10%
Normalized Cash Free Net Working Capital	21.00%	21.00%
Electrometallurgy Canada Segment
Disclosure of significant unobservable inputs used in fair value measurement of assets [abstract]
Weighted Average Cost of Capital	10.50%	10.50%
Long-Term Growth Rate	2.00%	1.50%
Normalized Tax Rate	26.50%	26.50%
Normalized Cash Free Net Working Capital	21.00%	21.00%

X

- Definition

Free net working capital percent used as a significant Level 3 unobservable input for assets.

+ References

No definition available.

+ Details

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- Definition

Long-term growth rate used as a significant Level 3 unobservable input for assets.

+ References

No definition available.

+ Details

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X

- Definition

Normalized tax rate used as a significant Level 3 unobservable input for assets.

+ References

No definition available.

+ Details

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- Definition

The term of projections used to determine significant Level 3 unobservable inputs for assets.

+ References

No definition available.

+ Details

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- References

No definition available.

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- Definition

Weighted average cost of capital used as a significant Level 3 unobservable input for assets. [Refer: Level 3 of fair value hierarchy [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Name IFRS
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