Summary of Significant Accounting Policies - Gains (Losses) Included in Other Comprehensive Income on Derivates Accounted for as Hedging Instruments, Net of Tax (Details) (Designated as Hedging Instrument [Member], Interest Rate Swap [Member], Cash Flow Hedging [Member], USD $) In Thousands, unless otherwise specified	May 31, 2013	Aug. 31, 2012	May 31, 2012
Designated as Hedging Instrument [Member] \| Interest Rate Swap [Member] \| Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax	$ 5,666

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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