Other Assets - Rollforward of Capitalized Maintenance Activity (Details) - USD ($) $ in Thousands	12 Months Ended
	Aug. 31, 2020	Aug. 31, 2019	Aug. 31, 2018
Capitalized Maintenance Expense [Roll Forward]
Balance at Beginning of Year	$ 286,890	$ 130,780	$ 105,006
Cost Deferred	14,496	224,406	87,460
Amortization	(72,875)	(68,296)	(61,686)
Balance at End of Year	$ 228,511	$ 286,890	$ 130,780