Business Segments (Summary of Certain Financial Information from Continuing Operations by Reportable Segment) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended																12 Months Ended
	Aug. 31, 2012		May 31, 2012		Feb. 29, 2012		Nov. 30, 2011		Aug. 31, 2011		May 31, 2011		Feb. 28, 2011		Nov. 30, 2010		Aug. 31, 2012		Aug. 31, 2011		Aug. 31, 2010
Segment Reporting Information [Line Items]
Net sales-unaffiliated customers	$ 1,878,147	[1]	$ 2,006,729	[1]	$ 1,956,744	[1]	$ 1,986,820	[1]	$ 2,243,920	[1]	$ 2,062,683	[1]	$ 1,781,650	[1]	$ 1,775,092	[1]	$ 7,828,440		$ 7,863,345		$ 6,276,928
Adjusted operating profit (loss)																	238,727		113,576		(83,256)
Capital expenditures																	113,853		73,215		127,121
Segment, Continuing Operations [Member]
Segment Reporting Information [Line Items]
Net sales-unaffiliated customers																	7,828,440		7,863,345		6,276,928
Intersegment sales																	0		0		0
Net sales																	7,828,440		7,863,345		6,276,928
Adjusted operating profit (loss)																	238,727		113,576		(83,256)
Interest expense																	69,496	[2]	69,821	[2]	74,181	[2]
Capital expenditures																	109,601	[3]	60,399	[3]	94,029	[3]
Depreciation and amortization																	137,289	[4]	178,251	[4]	165,316	[4]
Total assets	3,434,645	[5]							3,579,200	[5]							3,434,645	[5]	3,579,200	[5]	3,511,025	[5]
Americas Recycling [Member]
Segment Reporting Information [Line Items]
Net sales-unaffiliated customers																	1,418,717		1,692,824		1,211,815
Intersegment sales																	187,444		136,713		104,615
Net sales																	1,606,161		1,829,537		1,316,430
Adjusted operating profit (loss)																	39,446		43,059		11,416
Interest expense																	1,933	[2]	246	[2]	109	[2]
Capital expenditures																	40,329	[3]	7,666	[3]	5,430	[3]
Depreciation and amortization																	13,260	[4]	12,860	[4]	15,802	[4]
Total assets	285,136	[5]							278,120	[5]							285,136	[5]	278,120	[5]	228,781	[5]
Americas Mills [Member]
Segment Reporting Information [Line Items]
Net sales-unaffiliated customers																	1,378,716		1,308,055		869,014
Intersegment sales																	777,101		728,270		609,412
Net sales																	2,155,817		2,036,325		1,478,426
Adjusted operating profit (loss)																	233,933		161,731		37,251
Interest expense																	13,004	[2]	12,901	[2]	12,113	[2]
Capital expenditures																	39,356	[3]	25,657	[3]	32,244	[3]
Depreciation and amortization																	43,551	[4]	52,048	[4]	55,315	[4]
Total assets	676,909	[5]							650,920	[5]							676,909	[5]	650,920	[5]	622,358	[5]
Americas Fabrication [Member]
Segment Reporting Information [Line Items]
Net sales-unaffiliated customers																	1,366,944		1,208,823		1,131,928
Intersegment sales																	14,694		16,899		8,349
Net sales																	1,381,638		1,225,722		1,140,277
Adjusted operating profit (loss)																	(15,697)		(129,141)		(107,800)
Interest expense																	10,809	[2]	9,717	[2]	9,076	[2]
Capital expenditures																	4,389	[3]	2,029	[3]	2,948	[3]
Depreciation and amortization																	22,056	[4]	48,299	[4]	42,777	[4]
Total assets	629,970	[5]							590,278	[5]							629,970	[5]	590,278	[5]	622,608	[5]
International Mill [Member]
Segment Reporting Information [Line Items]
Net sales-unaffiliated customers																	955,730		1,043,267		621,230
Intersegment sales																	77,627		2,966		77,834
Net sales																	1,033,357		1,046,233		699,064
Adjusted operating profit (loss)																	23,044		47,594		(31,594)
Interest expense																	10,090	[2]	18,251	[2]	10,098	[2]
Capital expenditures																	14,016	[3]	14,278	[3]	39,376	[3]
Depreciation and amortization																	32,306	[4]	36,528	[4]	27,889	[4]
Total assets	529,160	[5]							643,748	[5]							529,160	[5]	643,748	[5]	546,356	[5]
International Marketing and Distribution [Member]
Segment Reporting Information [Line Items]
Net sales-unaffiliated customers																	2,700,300		2,603,494		2,439,018
Intersegment sales																	27,019		47,405		24,396
Net sales																	2,727,319		2,650,899		2,463,414
Adjusted operating profit (loss)																	47,287		76,337		74,689
Interest expense																	6,548	[2]	2,173	[2]	3,273	[2]
Capital expenditures																	3,314	[3]	2,873	[3]	7,118	[3]
Depreciation and amortization																	5,821	[4]	4,600	[4]	5,021	[4]
Total assets	870,933	[5]							990,111	[5]							870,933	[5]	990,111	[5]	732,900	[5]
Corporate [Member]
Segment Reporting Information [Line Items]
Net sales-unaffiliated customers																	8,033		6,882		3,923
Intersegment sales																	0		0		326
Net sales																	8,033		6,882		4,249
Adjusted operating profit (loss)																	(83,035)		(84,729)		(70,678)
Interest expense																	27,112	[2]	26,533	[2]	39,512	[2]
Capital expenditures																	8,197	[3]	7,896	[3]	6,913	[3]
Depreciation and amortization																	20,295	[4]	23,916	[4]	18,512	[4]
Total assets	961,654	[5]							1,505,672	[5]							961,654	[5]	1,505,672	[5]	1,083,744	[5]
Eliminations [Member]
Segment Reporting Information [Line Items]
Net sales-unaffiliated customers																	0		0		0
Intersegment sales																	(1,083,885)		(932,253)		(824,932)
Net sales																	(1,083,885)		(932,253)		(824,932)
Adjusted operating profit (loss)																	(6,251)		(1,275)		3,460
Interest expense																	0	[2]	0	[2]	0	[2]
Capital expenditures																	0	[3]	0	[3]	0	[3]
Depreciation and amortization																	0	[4]	0	[4]	0	[4]
Total assets	$ (519,117)	[5]							$ (1,079,649)	[5]							$ (519,117)	[5]	$ (1,079,649)	[5]	$ (325,722)	[5]

[1] *Excludes divisions classified as discontinued operations. See Note 9, Discontinued Operations.

[2] Includes intercompany interest expense (income) in the segments and is all eliminated within Corporate.

[3] Excludes capital expenditures from discontinued operations of $4.3 million at August 31, 2012, $12.8 million at August 31, 2011, and $33.1 million at August 31, 2010.

[4] Includes asset impairment charges.

[5] Excludes total assets from discontinued operations of $6.6 million at August 31, 2012, $103.9 million at August 31, 2011 and $195.1 million at August 31, 2010.