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Pensions and Other Postretirement Benefits - Effect of Changes in Assumed Health Care Cost Trend Rate (Detail) (USD $)
In Thousands, unless otherwise specified |
12 Months Ended |
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Aug. 31, 2012
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| Compensation And Retirement Disclosure [Abstract] | |
| Effect on total of service and interest cost components in fiscal 2012, one percentage point increase in health care trend rate | $ 180 |
| Effect on postretirement accumulated benefit obligation as of August 31, 2012, one percentage point increase in health care trend rate | 3,115 |
| Effect on total of service and interest cost components in fiscal 2012, one percentage point decrease in health care trend rate | (149) |
| Effect on postretirement accumulated benefit obligation as of August 31, 2012, one percentage point decrease in health care trend rate | $ (2,558) |