Number of agreements under collective bargaining arrangements that are to expire within the next twelve months.

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

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

+ References

No definition available.

+ Details

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- Definition

The number of locations under collective bargaining arrangements that expire within the next twelve months.

+ References

No definition available.

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- Definition

Workforce Subject To Collective Bargaining Arrangements Subject to Expire Percent

+ References

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=51824106&loc=d3e2420-110228

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3602-108585

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- Definition

Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 30
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6578-128477

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 30
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6613-128477

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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

No definition available.

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- Definition

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.

+ References

No definition available.

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Description of the Business and Significant Accounting Policies (Segments) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) segment item	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Segment Reporting Information
Workforce represented by collective bargaining agreements (as a percent)	9.00%
Number of collective bargaining agreements that expire \| item	6
Workforce Subject To Collective Bargaining Arrangements Subject to Expire Percent	7.00%
Number of locations subject to collective bargaining agreements that expire \| item	4
Impairment charges	$ 132,839	$ 428,500	$ 260,000
Segment Reporting Information
Number of reporting segments \| segment	3
Steel Operations
Segment Reporting Information
Percentage of external net sales	72.00%	69.00%	63.00%
Metals Recycling Operations
Segment Reporting Information
Percentage of external net sales	15.00%	19.00%	25.00%
Steel Fabrication Operations
Segment Reporting Information
Percentage of external net sales	9.00%	9.00%	7.00%
Mining Resources
Segment Reporting Information
Business Combination, Consideration Transferred	$ 15,100
Minnesota Ironmaking Operations
Segment Reporting Information
Impairment charges	127,300	$ 428,500	$ 260,000
Minnesota Ironmaking Operations \| Parent [Member]
Segment Reporting Information
Impairment charges	72,900		132,600
Minnesota Ironmaking Operations \| Noncontrolling Interests
Segment Reporting Information
Impairment charges	$ 13,100		$ 46,500