Debt (Details) - USD ($)	3 Months Ended
Nov. 30, 2016	Aug. 31, 2016
Debt [Line Items]
Total debt	$ 56,781,000	$ 90,795,000
Less short-term borrowings and current portion of long-term debt	(23,530,000)	(55,609,000)
Long-term debt	33,251,000	35,186,000
Letters of credit outstanding	28,000,000	29,000,000
Revolving credit facility [Member]
Debt [Line Items]
Total debt	0	$ 30,000,000
Borrowing capacity	625,000,000
Debt repaid	$ 30,000,000
Weighted average interest rate		3.80%
Revolving credit facility [Member] \| Minimum [Member]
Debt [Line Items]
Fees	0.25%
Revolving credit facility [Member] \| Minimum [Member] \| Prime Rate [Member]
Debt [Line Items]
Fees for borrowings	0.25%
Revolving credit facility [Member] \| Maximum [Member]
Debt [Line Items]
Fees	0.40%
Revolving credit facility [Member] \| Maximum [Member] \| Prime Rate [Member]
Debt [Line Items]
Fees for borrowings	0.85%
Capital Lease Obligations [Member]
Debt [Line Items]
Total debt	$ 25,565,000	$ 28,489,000
Notes Payable, Other Payables [Member]
Debt [Line Items]
Total debt	$ 31,216,000	$ 32,306,000
Weighted average interest rate	6.30%	6.00%

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.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.13,16)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.16)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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- Definition

Amount of short-term debt and current maturity of long-term debt and capital lease obligations due within one year or the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19,20)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

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Weighted average interest rate of debt outstanding.

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- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

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- Definition

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+ References

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- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

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- Definition

Amount of long-term debt and capital lease obligation due after one year or beyond the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Amount of cash outflow for payment of an obligation from a lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3291-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Financing Activities
-URI http://asc.fasb.org/extlink&oid=6513228

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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