Other Comprehensive Income (Loss) ("OCI") - Components of Accumulated Other Comprehensive Income (loss) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
Feb. 28, 2013	Feb. 29, 2012	Feb. 28, 2013	Feb. 29, 2012
Equity [Abstract]
Net Unrealized Gains (Losses) on Cash Flow Hedging Instruments, Beginning Balance			$ 1,638	$ 731
Net Unrealized Gains (Losses) on Cash Flow Hedging Instruments, Other comprehensive income (loss), net of taxes			(2,085)	(713)
Net Unrealized Gains (Losses) on Cash Flow Hedging Instruments, Ending Balance	(447)	18	(447)	18
Gains (Losses) on Postretirement Obligations, Beginning Balance			(17,231)	(8,290)
Gains (Losses) on Postretirement Obligations, Other comprehensive income (loss), net of taxes			710
Gains (Losses) on Postretirement Obligations, Ending Balance	(16,521)	(8,290)	(16,521)	(8,290)
Accumulated Other Comprehensive Loss, Beginning balance			(15,593)	(7,559)
Accumulated Other Comprehensive Loss, Other comprehensive income (loss), net of taxes	147	161	(1,375)	(713)
Accumulated Other Comprehensive Loss, Ending balance	$ (16,968)	$ (8,272)	$ (16,968)	$ (8,272)

Accumulated change, net of tax, in accumulated gains and losses from derivative instruments designated and qualifying as the effective portion of cash flow hedges. Includes an entity's share of an equity investee's Increase or Decrease in deferred hedging gains or losses.

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The total of net gain (loss), prior service cost (credit), and transition assets (obligations), as well as minimum pension liability if still remaining, included in accumulated other comprehensive income associated with a defined benefit pension or other postretirement plan(s) because they have yet to be recognized as components of net periodic benefit cost.

+ References

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- Definition

Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

+ References

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+ Details

- Definition

Net of tax amount of other comprehensive income (loss) attributable to the parent entity.

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