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Related Party Transactions - Narrative (Details) t in Thousands	12 Months Ended
	Dec. 31, 2018 t
Related Party Transaction [Line Items]
Glencore beneficial ownership	42.90%
Glencore economic ownership	47.20%
Major customer, percentage revenue, net	10.00%
BHH [Member]
Related Party Transaction [Line Items]
Ownership percentage, equity method	40.00%
Carbon anode production capacity, annual increase	12
Customer Concentration Risk [Member] | Sales Revenue, Goods, Net [Member] | Glencore [Member]
Related Party Transaction [Line Items]
Major customer, percentage revenue, net	64.00%

X

- Definition

Carbon Anode Production Capacity, Annual Increase

+ References

No definition available.

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- Definition

The percentage of common stock and preferred stock of the company owned by a related party.

+ References

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- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 275
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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

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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.

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