Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Aug. 31, 2020	Aug. 31, 2019
Deferred tax assets:
Accrued expenses	$ 51,560	$ 62,245
Postretirement health care and deferred compensation	42,898	42,747
Tax credit carryforwards	123,193	152,347
Loss carryforwards	116,741	136,435
Nonqualified equity	344,924	290,447
Deferred tax asset lease obligation	64,140
Other	85,856	97,071
Deferred tax assets valuation reserve	(219,891)	(246,344)
Total deferred tax assets	609,421	534,948
Deferred tax liabilities:
Pension	17,131	11,237
Investments	95,916	99,838
Deferred Tax Liabilities, Deferred Expense, Other Capitalized Costs	91	4,679
Property, plant and equipment	556,160	560,334
Deferred tax liability right of use asset	64,140
Other	15,326	1,760
Total deferred tax liabilities	748,764	677,848
Net deferred tax liabilities	$ 139,343	$ 142,900