Commitments and Contingencies (Details)	3 Months Ended
Mar. 31, 2013 item Complaint	Sep. 30, 2008 Company
Commitments and Contingencies
Number of other steel manufacturing companies also served with a class action antitrust complaint		8
Number of the complaints not brought on behalf of steel product purchasers	1
Number of Plaintiffs' retained experts	2

Represents the number of complaints received that were not brought on behalf of a class consisting of all direct purchasers of steel products.

No definition available.

Name:	stld_NumberOfComplaintsNotRelatedToSteelPurchasers
Namespace Prefix:	stld_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant