Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Aug. 31, 2019	Aug. 31, 2018
Deferred tax assets:
Accrued expenses	$ 62,245	$ 138,417
Postretirement health care and deferred compensation	42,747	41,797
Tax credit carryforwards	152,347	154,240
Loss carryforwards	136,435	104,519
Nonqualified equity	290,447	178,046
Major maintenance	0	5,484
Other	97,071	83,580
Deferred tax assets valuation reserve	(246,344)	(230,373)
Total deferred tax assets	534,948	475,710
Deferred tax liabilities:
Pension	11,237	19,397
Investments	99,838	98,608
Deferred Tax Liabilities, Deferred Expense, Other Capitalized Costs	4,679	0
Property, plant and equipment	560,334	513,238
Other	1,760	26,828
Total deferred tax liabilities	677,848	658,071
Net deferred tax liabilities	$ 142,900	$ 182,361