Business Segments (Summary of Certain Financial Information from Continuing Operations by Reportable Segment) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			9 Months Ended
	May 31, 2013		May 31, 2012	May 31, 2013		May 31, 2012	Aug. 31, 2012
Segment Reporting Information [Line Items]
Net sales-unaffiliated customers	$ 1,794,306		$ 2,006,729	$ 5,313,206		$ 5,950,293
Adjusted operating profit (loss)	55,752		67,770	172,684		176,130
Segment, Continuing Operations [Member]
Segment Reporting Information [Line Items]
Net sales-unaffiliated customers	1,794,306		2,006,729	5,313,206		5,950,293
Intersegment sales	0		0	0		0
Net sales	1,794,306		2,006,729	5,313,206		5,950,293
Adjusted operating profit (loss)	55,752		67,770	172,684		176,130
Total assets	3,583,826	[1]		3,583,826	[1]		3,434,645	[1]
Americas Recycling [Member]
Segment Reporting Information [Line Items]
Net sales-unaffiliated customers	300,866		364,195	909,372		1,114,185
Intersegment sales	40,877		48,217	135,706		132,676
Net sales	341,743		412,412	1,045,078		1,246,861
Adjusted operating profit (loss)	3,155		3,895	9,892		31,100
Total assets	272,678	[1]		272,678	[1]		285,136	[1]
Americas Mills [Member]
Segment Reporting Information [Line Items]
Net sales-unaffiliated customers	315,185		343,700	907,303		1,032,891
Intersegment sales	188,507		221,425	569,432		583,615
Net sales	503,692		565,125	1,476,735		1,616,506
Adjusted operating profit (loss)	47,511		59,285	148,802		171,617
Total assets	665,405	[1]		665,405	[1]		676,909	[1]
Americas Fabrication [Member]
Segment Reporting Information [Line Items]
Net sales-unaffiliated customers	380,629		375,097	1,047,765		988,840
Intersegment sales	3,171		4,229	10,593		11,847
Net sales	383,800		379,326	1,058,358		1,000,687
Adjusted operating profit (loss)	13,499		199	19,879		(17,150)
Total assets	649,338	[1]		649,338	[1]		629,970	[1]
International Mill [Member]
Segment Reporting Information [Line Items]
Net sales-unaffiliated customers	200,750		246,553	596,450		715,651
Intersegment sales	2		5,285	6,134		49,458
Net sales	200,752		251,838	602,584		765,109
Adjusted operating profit (loss)	(3,831)		1,277	(7,108)		17,691
Total assets	456,093	[1]		456,093	[1]		529,160	[1]
International Marketing and Distribution [Member]
Segment Reporting Information [Line Items]
Net sales-unaffiliated customers	592,988		677,859	1,841,968		2,094,050
Intersegment sales	816		5,549	10,360		22,784
Net sales	593,804		683,408	1,852,328		2,116,834
Adjusted operating profit (loss)	7,728		23,346	51,837		45,799
Total assets	868,978	[1]		868,978	[1]		870,933	[1]
Corporate [Member]
Segment Reporting Information [Line Items]
Net sales-unaffiliated customers	3,888		(675)	10,348		4,676
Intersegment sales	0		0	0		0
Net sales	3,888		(675)	10,348		4,676
Adjusted operating profit (loss)	(14,834)		(20,110)	(51,398)		(64,314)
Total assets	1,215,106	[1]		1,215,106	[1]		961,654	[1]
Eliminations [Member]
Segment Reporting Information [Line Items]
Net sales-unaffiliated customers	0		0	0		0
Intersegment sales	(233,373)		(284,705)	(732,225)		(800,380)
Net sales	(233,373)		(284,705)	(732,225)		(800,380)
Adjusted operating profit (loss)	2,524		(122)	780		(8,613)
Total assets	$ (543,772)	[1]		$ (543,772)	[1]		$ (519,117)	[1]

[1] Excludes total assets from discontinued operations of $3.8 million at May 31, 2013 and $6.6 million at August 31, 2012.