Discontinued Operations (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended		3 Months Ended
	May 31, 2012	May 31, 2011	May 31, 2012	May 31, 2011	Nov. 30, 2011 CMCS [Member]	May 31, 2012 Joist and Deck Operations [Member] properties
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Severance expense	$ 1.0	$ 1.3	$ 23.3	$ 2.6	$ 18.0
Real property						3