Benefit Plans - Schedule of Changes in the Fair value of the Plan's Level 3 Valued Assets (Details) (Pension Plans, Defined Benefit, USD $) In Thousands, unless otherwise specified	12 Months Ended
Aug. 31, 2012	Aug. 31, 2011
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balances at beginning of period	$ 14,713	$ 12,112
Unrealized gains (losses)	1,743	2,236
Realized losses (gains)	42
Sales	(10)
Purchases	26
Transfers into level 3	1,738
Purchases, sales, issuances and settlements, net		365
Total	18,252	14,713
Real Estate Funds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balances at beginning of period	14,522	9,407
Unrealized gains (losses)	1,763	2,104
Realized losses (gains)	(48)
Sales	(2)
Purchases	22
Purchases, sales, issuances and settlements, net		3,011
Total	16,257	14,522
Hedge funds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balances at beginning of period	191	2,705
Unrealized gains (losses)	(68)	132
Realized losses (gains)
Sales
Purchases	4
Purchases, sales, issuances and settlements, net		(2,646)
Total	127	191
Mutual Funds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balances at beginning of period	0
Unrealized gains (losses)	48
Realized losses (gains)	90
Sales	(8)
Transfers into level 3	1,738
Total	$ 1,868

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Amount of gain (loss) recognized in earnings, arising from assets measured at fair value on a recurring basis using unobservable inputs (level 3).

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Amount of gain (loss) recognized in other comprehensive income, arising from assets measured at fair value on a recurring basis using unobservable inputs (level 3).

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- Definition

Purchases that have taken place during the period in relation to assets measured at fair value and categorized within Level 3 of the fair value hierarchy.

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- Definition

Amount of purchases, sales, issues, and settlements (net) which have taken place in relation to assets measured at fair value on a recurring basis using unobservable inputs (level 3).

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 157

-Paragraph 32

-Subparagraph c(2)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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Sales that have taken place during the period in relation to assets measured at fair value and categorized within Level 3 of the fair value hierarchy.

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Transfers into assets measured at fair value and categorized within Level 3 of the fair value hierarchy that have taken place during the period.

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- Definition

This element represents an asset measured at fair value using significant unobservable inputs (Level 3) which is required for reconciliation purposes of beginning and ending balances.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 157

-Paragraph 32

-Subparagraph c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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