Long-term Debt and Capital Lease Obligations Current and Non Current (Detail) (USD $) In Thousands, unless otherwise specified	Aug. 31, 2012	Aug. 31, 2011
Debt Instrument [Line Items]
Capital lease obligations	$ 423	$ 490
Debt and capital lease obligations, including current portion and short-term borrowings	84,462	24,223
Less: current portion and short-term borrowings	458	421
Long-term debt and capital lease obligations	84,004	23,802
Secured Debt [Member]
Debt Instrument [Line Items]
Carrying amount of debt	82,606	22,100
Secured credit agreements - weighted average interest rate (in percentage)	4.23%
Iowa Department Of Economic Development loans [Member]
Debt Instrument [Line Items]
Carrying amount of debt	$ 1,433	$ 1,633

Amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal through the balance sheet date.

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

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-Name Regulation S-X (SX)

-Number 210

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

-Publisher FASB

-Name Accounting Standards Codification

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-Section 50

-Paragraph 1

-Subparagraph (b)

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Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, and capital lease obligations.

+ References

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-Publisher FASB

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- Definition

Including current and noncurrent portions, aggregate carrying amount of long-term borrowings as of the balance sheet date before deducting unamortized discount or premiums (if any). May include notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, which had initial maturities beyond one year or beyond the normal operating cycle, if longer.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

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

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-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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Reflects the calculation as of the balance sheet date of the average interest rate weighted by the amount of debt outstanding by type or by instrument at that time.

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No definition available.

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- Definition

Sum of the carrying values as of the balance sheet date of all long-term debt, which is debt initially having maturities due after one year from the balance sheet date or beyond the operating cycle, if longer, but excluding the portions thereof scheduled to be repaid within one year or the normal operating cycle, if longer plus capital lease obligations due to be paid more than one year after the balance sheet date.

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Obligation related to long-term debt (excluding convertible debt) and capital leases, the portion which is due in one year or less in the future.

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