Derivatives (Narrative) (Details) (Natural Gas Forward Purchase Contracts [Member], USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2012
Natural Gas Forward Purchase Contracts [Member]
Derivative [Line Items]
Net deferred losses on cash flow hedges on these contracts that are included in accumulated other comprehensive income that are expected to be reclassified into earnings during the next nine months	$ 31.7
Reclassification of earnings, time period, in months	9

The estimated net amount of existing gains or losses on cash flow hedges at the reporting date expected to be reclassified to earnings within the next 9 months.

No definition available.

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Namespace Prefix:	nue_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration