Business Segments (External Net Sales from Continuing Operations by Major Product) (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
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales	$ 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
Steel products [Member]
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																	4,700,854	4,414,105	3,622,429
Industrial materials [Member]
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																	1,147,386	1,134,819	913,019
Nonferrous scrap [Member]
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																	765,349	997,771	702,467
Ferrous scrap [Member]
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																	763,772	805,067	561,119
Construction materials [Member]
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																	177,827	217,741	220,993
Nonferrous products [Member]
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																	171,861	196,641	178,844
Other [Member]
Entity-Wide Information, Revenue from External Customer [Line Items]
Net sales																	$ 101,391	$ 97,201	$ 78,057

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