Allowance for Uncollectible Trade Accounts Receivables (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Aug. 31, 2012	Aug. 31, 2011	Aug. 31, 2010
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at end of period	$ 3,237	$ 4,788
Allowance for uncollectible trade accounts receivable
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of period	4,788	13,939	15,510
Additions and adjustments charged to costs and expenses	564	5,179	(881)
Additions/(Reductions) charged to other accounts		(6,428)
Write-offs	(2,115)	(7,902)	(690)
Balance at end of period	$ 3,237	$ 4,788	$ 13,939