Segments (Details) (USD $) In Thousands	3 Months Ended		9 Months Ended
	Oct. 01, 2011	Oct. 02, 2010	Oct. 01, 2011	Oct. 02, 2010	Dec. 31, 2010
Net sales to external customers	$ 5,252,144	$ 4,140,069	$ 15,193,887	$ 11,990,877
Intercompany sales
Earnings (loss) before income taxes and noncontrolling interests	284,215	58,006	1,027,757	277,615
Segment assets	14,807,265		14,807,265		13,921,910
Steel Mills [Member]
Net sales to external customers	3,617,867	2,798,419	10,635,850	8,285,773
Intercompany sales	599,005	451,792	1,815,673	1,255,562
Earnings (loss) before income taxes and noncontrolling interests	436,196	231,803	1,375,614	652,450
Segment assets	6,399,240		6,399,240		5,969,846
Steel Products [Member]
Net sales to external customers	958,224	794,289	2,565,728	2,093,017
Intercompany sales	14,444	12,351	38,691	33,533
Earnings (loss) before income taxes and noncontrolling interests	(10,527)	(40,826)	(56,432)	(143,817)
Segment assets	3,020,188		3,020,188		2,835,812
Raw Materials [Member]
Net sales to external customers	535,948	463,515	1,618,956	1,364,340
Intercompany sales	2,572,705	1,839,956	8,047,832	6,156,283
Earnings (loss) before income taxes and noncontrolling interests	22,481	7,444	131,761	93,997
Segment assets	2,944,040		2,944,040		2,710,544
All Other [Member]
Net sales to external customers	140,105	83,846	373,353	247,747
Intercompany sales	4,742	2,248	21,093	6,988
Earnings (loss) before income taxes and noncontrolling interests	737	(613)	5,014	3,955
Segment assets	173,609		173,609		170,174
Corporate/Eliminations [Member]
Intercompany sales	(3,190,896)	(2,306,347)	(9,923,289)	(7,452,366)
Earnings (loss) before income taxes and noncontrolling interests	(164,672)	(139,802)	(428,200)	(328,970)
Segment assets	$ 2,270,188		$ 2,270,188		$ 2,235,534