Income Taxes - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Aug. 31, 2021	Aug. 31, 2020	Aug. 31, 2019
Operating Loss Carryforwards [Line Items]
Income tax benefit	$ (38,249)	$ (36,731)	$ (12,456)
Deferred Tax Liabilities, Net	101,528	139,343
Income (Loss) from Continuing Operations before Income Taxes, Domestic	497,500	324,400	825,700
Income (Loss) from Continuing Operations before Income Taxes, Foreign	$ 17,800	$ 62,500	$ (3,100)
Statutory federal income tax rate	21.00%	21.00%	21.00%
Operating Loss Carryforwards	$ 527,500
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	304,400
Amount of unrecognized tax benefits that would benefit effective tax rate	114,300
Unrecognized Tax Benefits, Interest on Income Taxes Expense	1,400	$ 1,000	$ 1,700
Unrecognized Tax Benefits, Interest on Income Taxes Accrued	2,500	1,000	$ 2,900
State tax credit
Operating Loss Carryforwards [Line Items]
Tax credit carryforward, amount	129,700
Low sulfer diesel credits
Operating Loss Carryforwards [Line Items]
Tax credit carryforward, amount	44,100
NCRA | State tax credit
Operating Loss Carryforwards [Line Items]
Tax credit carryforward, amount	$ 129,700	$ 125,500