Commitments And Contingencies (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Aug. 31, 2012	Aug. 31, 2011	Aug. 31, 2010
Commitments And Contingencies [Abstract]
Estimated accrual as operating expense	$ 7.2
Lease expense	$ 3.6	$ 3.4	$ 2.8

Undiscounted amount of the accrual for environmental loss contingencies maturing in the next fiscal year following the latest fiscal year.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section S99

-Paragraph 1

-Subparagraph (SAB TOPIC 5.Y.Q1)

-URI http://asc.fasb.org/extlink&oid=6572457&loc=d3e149879-122751

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

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 5

-Section Y

-Paragraph Question 1

Name:	us-gaap_AccrualForEnvironmentalLossContingenciesUndiscountedDueWithinOneYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant