Derivatives And Risk Management (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
Aug. 31, 2012	Aug. 31, 2012	Aug. 31, 2011	Aug. 31, 2010
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Notional amount of interest rate derivatives terminated	$ 800
Increase (Decrease) in Fair Value of Hedged Item in Interest Rate Fair Value Hedge			48.6
Reduction in interest expense related to interest rate swaps		$ 6.5	$ 15.7	$ 5.7

Amount of unrealized gain (loss) included in earnings related to the fair value of the hedged item in an interest rate fair value hedge, offset by the gain (loss) on the hedging instrument to the extent that the fair value hedge is determined to be effective.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4A

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5618551-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4C

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624171-113959

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration