Represents the annual anticipated production capacity of facility.

No definition available.

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- Definition

Represents the actual annual production of facility.

+ References

No definition available.

+ Details

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Namespace Prefix:	stld_
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- Definition

Number of agreements under collective bargaining arrangements.

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
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- Definition

Represents number of galvanizing lines to be used in galvanizing of specific types of flat rolled steels in non-automotive applications.

+ References

No definition available.

+ Details

Name:	stld_NumberOfGalvanizingLines
Namespace Prefix:	stld_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of iron making initiatives.

+ References

No definition available.

+ Details

Name:	stld_NumberOfIronMakingInitiatives
Namespace Prefix:	stld_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of plants.

+ References

No definition available.

+ Details

Name:	stld_NumberOfPlants
Namespace Prefix:	stld_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of years subsequent to achievement of certain performance measures.

+ References

No definition available.

+ Details

Name:	stld_NumberOfYearsSubsequentToAchievementOfPerformanceMeasures
Namespace Prefix:	stld_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of ownership interest in facility.

+ References

No definition available.

+ Details

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Namespace Prefix:	stld_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

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Namespace Prefix:	stld_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of reportable segments of the entity.

+ References

No definition available.

+ Details

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Namespace Prefix:	stld_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- 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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Namespace Prefix:	stld_
Data Type:	num:percentItemType
Balance Type:	na
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- Definition

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

+ References

No definition available.

+ Details

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Namespace Prefix:	stld_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of locations under collective bargaining arrangements.

+ References

No definition available.

+ Details

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Namespace Prefix:	stld_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Details

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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://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 480

-SubTopic 10

-Subparagraph (12)(c)

-Section S99

-Paragraph 3A

-URI http://asc.fasb.org/extlink&oid=6802392&loc=SL6540498-122764

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 480

-SubTopic 10

-Subparagraph 14

-Paragraph 3A

-Section S99

-URI http://asc.fasb.org/extlink&oid=6802392&loc=SL6540498-122764

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Emerging Issues Task Force (EITF)

-Number D-98

-Paragraph 43

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 480

-SubTopic 10

-Subparagraph 15

-Paragraph 3A

-Section S99

-URI http://asc.fasb.org/extlink&oid=6802392&loc=SL6540498-122764

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Emerging Issues Task Force (EITF)

-Number D-98

-Paragraph 43

-Subparagraph c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 51

-Paragraph 27

-Appendix A

-Subparagraph c

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 480

-SubTopic 10

-Subparagraph (16)(c)

-Paragraph 3A

-Section S99

-URI http://asc.fasb.org/extlink&oid=6802392&loc=SL6540498-122764

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

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Description of the Business and Summary of Significant Accounting Policies (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Description of the Business and Summary of Significant Accounting Policies
Number of reporting segments	3
Workforce represented by collective bargaining agreements (as a percent)	11.00%
Number of collective bargaining agreements	2
Number of employees under collective bargaining agreements	72
Number of locations subject to collective bargaining	2
Number of iron making initiatives	2
Segment Reporting Information
Redeemable noncontrolling interests	70,694	54,294
Mesabi Nugget
Segment Reporting Information
Number of years subsequent to achievement of performance measures	3
Steel Operations
Segment Reporting Information
Percentage of external net sales	61.00%	61.00%	63.00%
Flat Roll Division
Segment Reporting Information
Percentage of external net sales	27.00%	28.00%	28.00%
Number of galvanizing lines	3
Metals Recycling and Ferrous Resources Operations
Segment Reporting Information
Percentage of external net sales	35.00%	35.00%	31.00%
Redeemable noncontrolling interests	65,700	54,300
Metals Recycling and Ferrous Resources Operations \| Mesabi Nugget
Segment Reporting Information
Percentage of ownership interest in facility	81.00%
Anticipated annual production capacity of facility (in metric tons)	500,000
Actual annual production of facility (in metric tons)	156,000	75,000
Metals Recycling and Ferrous Resources Operations \| Mining Resources
Segment Reporting Information
Percentage of ownership interest in facility	80.00%
Redeemable noncontrolling interests	5,000
Steel Fabrication Operations
Segment Reporting Information
Percentage of external net sales	3.00%	3.00%	4.00%
Number of plants	6