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Commitments and Contingencies - Additional Information (Detail) (USD $)
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3 Months Ended | |
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Aug. 31, 2012
Year
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May 31, 2012
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| Commitments and Contingencies Disclosure [Line Items] | ||
| Environmental remediation expense, period of remediation, years | 5 | |
| Estimated liability costs of remediation | $ 916,000 | $ 916,000 |
| Estimated liability, measurement period, years | 15 | |
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Minimum
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| Commitments and Contingencies Disclosure [Line Items] | ||
| Environmental remediation expense | 50,000 | |
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Maximum
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| Commitments and Contingencies Disclosure [Line Items] | ||
| Environmental remediation expense | $ 105,000 |
| X | ||||||||||
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- Definition
Accrual For Environmental Loss Contingencies Undiscounted Estimated Period No definition available.
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| X | ||||||||||
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- Details
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| X | ||||||||||
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- Definition
Environmental Remediation Expense, Period Of Remediation No definition available.
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| X | ||||||||||
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- Definition
Carrying value of the obligation (known or estimated) arising from requirements to perform activities to remediate one or more sites, payable after twelve months or beyond the next operating cycle if longer. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
The charge against earnings in the period for known or estimated future costs arising from requirements to perform environmental remediation activities. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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