Accumulated Other Comprehensive Loss - Components of Accumulated Other Comprehensive Income (Loss) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Aug. 31, 2013	Aug. 31, 2012	Aug. 31, 2011
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ (15,593)	$ (7,559)	$ (13,850)
Other comprehensive income (loss), net of taxes	7,974	(8,034)	6,291
Ending Balance	(7,619)	(15,593)	(7,559)
Net Unrealized Gains (Losses) on Cash Flow Hedging Instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	1,638	731	(582)
Other comprehensive income (loss), net of taxes	(2,494)	907	1,313
Ending Balance	(856)	1,638	731
Gains (Losses) on Postretirement Obligations [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(17,231)	(8,290)	(13,268)
Other comprehensive income (loss), net of taxes	10,468	(8,941)	4,978
Ending Balance	$ (6,763)	$ (17,231)	$ (8,290)

- 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.

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