Business Segments (Summary of Certain Financial Information from Continuing Operations by Reportable Segment) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			6 Months Ended
	Feb. 28, 2013		Feb. 29, 2012	Feb. 28, 2013		Feb. 29, 2012	Aug. 31, 2012
Segment Reporting Information [Line Items]
Net sales-unaffiliated customers	$ 1,729,674		$ 1,956,744	$ 3,518,900		$ 3,943,564
Adjusted operating profit (loss)	26,717		60,685	116,932		108,360
Segment, Continuing Operations [Member]
Segment Reporting Information [Line Items]
Net sales-unaffiliated customers	1,729,674		1,956,744	3,518,900		3,943,564
Intersegment sales	0		0	0		0
Net sales	1,729,674		1,956,744	3,518,900		3,943,564
Adjusted operating profit (loss)	26,717		60,685	116,932		108,360
Total assets	3,405,607	[1]		3,405,607	[1]		3,434,645
Americas Recycling [Member]
Segment Reporting Information [Line Items]
Net sales-unaffiliated customers	301,035		376,597	608,506		749,990
Intersegment sales	50,339		43,047	94,829		84,459
Net sales	351,374		419,644	703,335		834,449
Adjusted operating profit (loss)	2,243		6,389	6,737		27,205
Total assets	297,604	[1]		297,604	[1]		285,136	[1]
Americas Mills [Member]
Segment Reporting Information [Line Items]
Net sales-unaffiliated customers	285,302		344,625	592,118		689,191
Intersegment sales	191,292		181,260	380,925		362,190
Net sales	476,594		525,885	973,043		1,051,381
Adjusted operating profit (loss)	48,769		54,401	101,291		112,332
Total assets	664,628	[1]		664,628	[1]		676,909	[1]
Americas Fabrication [Member]
Segment Reporting Information [Line Items]
Net sales-unaffiliated customers	314,389		298,226	667,136		613,743
Intersegment sales	3,577		3,367	7,422		7,618
Net sales	317,966		301,593	674,558		621,361
Adjusted operating profit (loss)	(3,812)		(9,969)	6,380		(17,349)
Total assets	631,393			631,393			629,970
International Mill [Member]
Segment Reporting Information [Line Items]
Net sales-unaffiliated customers	179,842		216,177	395,700		469,098
Intersegment sales	(77)		913	6,132		44,173
Net sales	179,765		217,090	401,832		513,271
Adjusted operating profit (loss)	(4,153)		6,592	(3,277)		16,414
Total assets	513,525	[1]		513,525	[1]		529,160
International Marketing and Distribution [Member]
Segment Reporting Information [Line Items]
Net sales-unaffiliated customers	645,445		715,828	1,248,980		1,416,191
Intersegment sales	4,491		7,527	9,544		17,235
Net sales	649,936		723,355	1,258,524		1,433,426
Adjusted operating profit (loss)	3,948		26,554	44,109		22,453
Total assets	913,921	[1]		913,921	[1]		870,933
Corporate [Member]
Segment Reporting Information [Line Items]
Net sales-unaffiliated customers	3,661		5,291	6,460		5,351
Intersegment sales	0		0	0		0
Net sales	3,661		5,291	6,460		5,351
Adjusted operating profit (loss)	(19,194)		(20,936)	(36,564)		(44,204)
Total assets	916,921			916,921			961,654	[1]
Eliminations [Member]
Segment Reporting Information [Line Items]
Net sales-unaffiliated customers	0		0	0		0
Intersegment sales	(249,622)		(236,114)	(498,852)		(515,675)
Net sales	(249,622)		(236,114)	(498,852)		(515,675)
Adjusted operating profit (loss)	(1,084)		(2,346)	(1,744)		(8,491)
Total assets	$ (532,385)			$ (532,385)			$ (519,117)	[1]

[1] Excludes total assets from discontinued operations of $3.9 million at February 28, 2013 and $6.6 million at August 31, 2012.