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Business Segments - Major Customers (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Two Customers | Sales Revenue | Customer Concentration Risk
Revenue, Major Customer [Line Items]
Major customer, percentage revenue, net	10.00%
Glencore
Revenue, Major Customer [Line Items]
Revenues	$ 1,337.0	$ 1,025.5	$ 1,191.6
Glencore | Sales Revenue | Customer Concentration Risk
Revenue, Major Customer [Line Items]
Major customer, percentage revenue, net	60.00%	64.00%	65.00%
Southwire
Revenue, Major Customer [Line Items]
Revenues	$ 304.6	$ 195.9	$ 235.4

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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.

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