Represents the number of electric arc furnace steel mills.

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- Definition

The number of locations under collective bargaining arrangements.

+ References

No definition available.

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- Definition

The number of locations under collective bargaining arrangements expiring during the year.

+ References

No definition available.

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- Definition

The percentage of employees covered by a collective bargaining agreement as of the balance sheet date.

+ References

No definition available.

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- Definition

The percentage of employees covered by a collective bargaining agreement expiring during the year.

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No definition available.

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- Definition

Percentage of net revenue of the entity's external sales accounted for by the reportable unit.

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No definition available.

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- Definition

Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

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- Definition

Percentage of voting equity interests acquired at the acquisition date in the business combination.

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- Definition

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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As of the reporting date, the aggregate carrying amount of all noncontrolling interests which are redeemable by the (parent) entity (1) at a fixed or determinable price on a fixed or determinable date, (2) at the option of the holder of the noncontrolling interest, or (3) upon occurrence of an event that is not solely within the control of the (parent) entity. This item includes noncontrolling interest holder's ownership (or holders' ownership) regardless of the type of equity interest (common, preferred, other) including all potential organizational (legal) forms of the investee entity.

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Percentage of subsidiary's or equity method investee's stock owned by parent immediately after all stock transactions.

+ References

No definition available.

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Description of the Business and Summary of Significant Accounting Policies (Description of the Business) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) item segment	Dec. 31, 2019 USD ($)	Dec. 31, 2018	Mar. 01, 2019
Segment Reporting Information
Number of reporting segments \| segment	3
Workforce represented by collective bargaining agreements (as a percent)	7.00%
Number of locations under collective bargaining arrangements \| item	6
Percentage of workforce subject to collective bargaining arrangements expiring during the year	1.00%
Number of locations subject to collective bargaining agreements expiring \| item	2
Impairment charges \| $	$ 19,409
Redeemable noncontrolling interests \| $	$ 158,614	$ 143,614
Steel Operations
Segment Reporting Information
Number of electric arc furnace steel mills \| item	6
Percentage of external net sales	74.00%	76.00%	75.00%
Metals Recycling Operations
Segment Reporting Information
Percentage of external net sales	11.00%	11.00%	13.00%
Steel Fabrication Operations
Segment Reporting Information
Percentage of external net sales	9.00%	9.00%	8.00%
United Steel Supply, LLC
Segment Reporting Information
Acquisition of interest (as a percent)				75.00%
Mesabi Nugget
Segment Reporting Information
Noncontrolling interest, ownership percentage	84.00%	84.00%
Redeemable noncontrolling interests \| $	$ 111,200	$ 111,200