Commitments And Contingencies (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended						12 Months Ended
	Aug. 31, 2012	Aug. 31, 2011	Aug. 31, 2010	Aug. 31, 2012 Guarantee of Indebtedness of Others [Member]	Aug. 31, 2012 Class Action Antitrust Lawsuit [Member] states	Sep. 18, 2008 Class Action Antitrust Lawsuit [Member] entities	Aug. 31, 2012 CERCLA sites [Member]	Aug. 31, 2011 CERCLA sites [Member]
Commitments and Contingencies Disclosure [Abstract]
Operating leases, rent Expense	$ 43.9	$ 45.9	$ 48.9
Accrual for Environmental Loss Contingencies	9.0	16.3
Accrued Environmental Loss Contingencies, Noncurrent	4.9	5.1
Loss Contingencies [Line Items]
Number of steel manufacturing companies						9
Number of States					28
Environmental Remediation Expense							1.0	1.0
Maximum credit facility				4.0
Guarantor obligations, maximum exposure				$ 3.0