Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			6 Months Ended
	Feb. 29, 2012 segments		Feb. 28, 2011	Feb. 29, 2012 segments		Feb. 28, 2011	Aug. 31, 2011
Segment Reporting Information [Line Items]
Number Of Operating and Reporting Segments	3			3
Total revenues	$ 886,612		$ 721,842	$ 1,698,787		$ 1,396,946
Operating Income (loss)	17,987		45,937	32,955		74,377
Other income (expense)	(2,855)		1,931	(6,520)		1,549
Income from continuing operations before income taxes	15,132		47,868	26,435		75,926
Total assets	1,873,787			1,873,787			1,890,169
Investments in joint venture partnerships	17,654			17,654			17,208
Metal Recycling Business [Member]
Segment Reporting Information [Line Items]
Revenues including intercompany	781,933		637,028	1,510,371		1,228,736
Less: Intersegment revenues	(39,986)		(39,049)	(98,700)		(70,758)
Total revenues	741,947		597,979	1,411,671		1,157,978
Operating Income (loss)	19,952		41,691	33,051		67,225
Total assets	1,658,143	[1]		1,658,143	[1]		1,668,778	[1]
Investments in joint venture partnerships	18,000			18,000			17,000
Auto Parts Business [Member]
Segment Reporting Information [Line Items]
Revenues including intercompany	78,232		72,533	162,285		139,214
Less: Intersegment revenues	(18,090)		(18,738)	(39,593)		(33,949)
Total revenues	60,142		53,795	122,692		105,265
Operating Income (loss)	8,708		15,957	19,150		29,996
Total assets	319,665			319,665			304,060
Steel Manufacturing Business [Member]
Segment Reporting Information [Line Items]
Total revenues	84,523		70,068	164,424		133,703
Operating Income (loss)	(868)		(711)	349		(2,746)
Total assets	324,247			324,247			324,596
Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating Income (loss)	27,792		56,937	52,550		94,475
Total assets	2,302,055			2,302,055			2,297,434
Corporate Elimination [Member]
Segment Reporting Information [Line Items]
Operating Income (loss)	(9,805)		(11,000)	(19,595)		(20,098)
Total assets	$ (428,268)			$ (428,268)			$ (407,265)

[1] MRB total assets include $18 million and $17 million as of February 29, 2012 and August 31, 2011, respectively, for investments in joint venture partnerships.