Other Assets - Rollforward of Capitalized Maintenance Activity (Details) - USD ($) $ in Thousands	12 Months Ended
	Aug. 31, 2018	Aug. 31, 2017	Aug. 31, 2016
Capitalized Maintenance Expense [Roll Forward]
Balance at Beginning of Year	$ 105,006	$ 169,054	$ 241,588
Cost Deferred	87,460	3,010	949
Amortization	(61,686)	(67,058)	(73,483)
Balance at End of Year	$ 130,780	$ 105,006	$ 169,054