Other Assets - Rollforward of Capitalized Maintenance Activity (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Aug. 31, 2012	Aug. 31, 2011	Aug. 31, 2010
Capitalized Maintenance Expense [Roll Forward]
Balance at Beginning of Year	$ 80,752	$ 19,097	$ 30,075
Cost Deferred	23,443	92,129	7,554
Amortization	(33,641)	(30,474)	(18,532)
Write-Offs
Balance at End of Year	$ 70,554	$ 80,752	$ 19,097