Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011 Segment	Dec. 31, 2010	Dec. 31, 2009
Segment Information
Number of reporting segments									3
Segment Reporting Information
Net Sales, External									$ 7,519,048	$ 5,948,184	$ 3,772,948
Net Sales, External Non-U.S.									478,452	352,703	185,858
Total net sales	1,858,345	2,043,455	2,079,731	2,015,969	1,528,134	1,584,164	1,632,799	1,555,790	7,997,500	6,300,887	3,958,806
Operating income (loss)	82,490	108,785	188,219	205,326	46,821	69,000	116,635	132,297	584,820	364,753	119,531
Income (loss) before income taxes									424,319	213,459	(18,237)
Depreciation and amortization									222,607	224,698	221,426
Capital expenditures									167,007	133,394	330,052
Assets	5,979,226				5,589,934				5,979,226	5,589,934	5,129,872
Liabilities	3,608,632				3,458,804				3,608,632	3,458,804	3,126,607
Steel Operations
Segment Reporting Information
Net Sales, External									4,676,898	3,726,869	2,443,709
Net Sales, External Non-U.S.									182,319	103,061	67,394
Net Sales, Other segments									211,089	169,709	95,866
Total net sales									5,070,306	3,999,639	2,606,969
Operating income (loss)									658,120	439,795	196,225
Income (loss) before income taxes									574,108	363,352	127,701
Depreciation and amortization									108,477	112,471	104,184
Capital expenditures									43,998	51,695	68,968
Assets	2,598,767				2,551,885				2,598,767	2,551,885	2,373,700
Liabilities	495,425				422,764				495,425	422,764	330,949
Metals Recycling and Ferrous Resources Operations
Segment Reporting Information
Net Sales, External									2,473,511	1,966,518	1,121,803
Net Sales, External Non-U.S.									295,552	248,870	118,351
Net Sales, Other segments									1,383,505	963,644	441,979
Total net sales									4,152,568	3,179,032	1,682,133
Operating income (loss)									26,597	19,686	(4,709)
Income (loss) before income taxes									(16,706)	(26,988)	(42,360)
Depreciation and amortization									101,893	102,027	105,627
Capital expenditures									103,142	55,982	251,695
Assets	2,561,722				2,464,835				2,561,722	2,464,835	2,318,827
Liabilities	528,629				444,170				528,629	444,170	453,225
Steel Fabrication Operations
Segment Reporting Information
Net Sales, External									275,783	177,055	156,499
Net Sales, Other segments									625	323	1,509
Total net sales									276,408	177,378	158,008
Operating income (loss)									(6,584)	(25,056)	(6,356)
Income (loss) before income taxes									(13,573)	(30,539)	(11,861)
Depreciation and amortization									6,751	5,894	6,060
Capital expenditures									2,205	492	(473)
Assets	227,663				206,810				227,663	206,810	169,416
Liabilities	13,768				18,361				13,768	18,361	25,208
Other
Segment Reporting Information
Net Sales, External									92,856	77,742	50,937
Net Sales, External Non-U.S.									581	772	113
Net Sales, Other segments									11,711	9,841	5,796
Total net sales									105,148	88,355	56,846
Operating income (loss)									(95,141)	(66,189)	(45,356)
Income (loss) before income taxes									(121,233)	(88,007)	(68,793)
Depreciation and amortization									5,690	4,493	5,555
Capital expenditures									17,662	28,857	12,443
Assets	789,322				562,961				789,322	562,961	469,389
Liabilities	2,759,894				2,746,798				2,759,894	2,746,798	2,514,423
Eliminations
Segment Reporting Information
Net Sales, Other segments									(1,606,930)	(1,143,517)	(545,150)
Total net sales									(1,606,930)	(1,143,517)	(545,150)
Operating income (loss)									1,828	(3,483)	(20,273)
Income (loss) before income taxes									1,723	(4,359)	(22,924)
Depreciation and amortization									(204)	(187)
Capital expenditures										(3,632)	(2,581)
Assets	(198,248)				(196,557)				(198,248)	(196,557)	(201,460)
Liabilities	$ (189,084)				$ (173,289)				$ (189,084)	$ (173,289)	$ (197,198)