Number of operating electric arc furnace steel mills.

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- Definition

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

+ References

No definition available.

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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.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8672-108599

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- Definition

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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 480
-SubTopic 10
-Section S99
-Paragraph 3A
-Subparagraph (16)(c)
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-Topic 480
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-Section S99
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-URI http://asc.fasb.org/extlink&oid=65877616&loc=SL6540498-122764

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- References

No definition available.

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- Definition

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 Significant Accounting Policies (Description of the Business) (Details) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2021 USD ($)	Jun. 30, 2020	Jun. 30, 2021 USD ($) item segment	Jun. 30, 2020	Dec. 31, 2020 USD ($)
Segment Reporting Information
Number of reporting segments \| segment			3
Redeemable noncontrolling interests	$ 176,414		$ 176,414		$ 158,614
Steel Operations
Segment Reporting Information
Number of operating electric arc furnace steel mills \| item			6
Percentage of external net sales	72.00%	78.00%	72.00%	76.00%
Metals Recycling Operations
Segment Reporting Information
Percentage of external net sales	13.00%	7.00%	13.00%	10.00%
Steel Fabrication Operations
Segment Reporting Information
Percentage of external net sales	7.00%	10.00%	7.00%	9.00%
United Steel Supply, LLC
Segment Reporting Information
Noncontrolling interest, ownership percentage			75.00%		75.00%
Redeemable noncontrolling interests	$ 65,200		$ 65,200		$ 47,400
Mesabi Nugget
Segment Reporting Information
Noncontrolling interest, ownership percentage			84.00%		84.00%
Redeemable noncontrolling interests	$ 111,200		$ 111,200		$ 111,200