Organization, Basis of Presentation and Significant Accounting Policies (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Aug. 31, 2018 USD ($)	Aug. 31, 2018 USD ($)
Derivative Instruments, Gain (Loss) [Line Items]
Intangible assets with indefinite useful lives	$ 0	$ 0
Tax Act, provisionally recorded net benefit, revaluation of U.S. net deferred tax liability		155,200
Reclassification of tax effects to retained earnings		0
Accumulated Other Comprehensive Loss
Derivative Instruments, Gain (Loss) [Line Items]
Reclassification of tax effects to retained earnings	(27,000)	(26,992)
Capital Reserves
Derivative Instruments, Gain (Loss) [Line Items]
Reclassification of tax effects to retained earnings	$ 27,000	$ 26,992
Minimum | Major Maintenance Activities
Derivative Instruments, Gain (Loss) [Line Items]
Expenditures of turnarounds, capitalization period		2 years
Minimum | Other Intangible Assets
Derivative Instruments, Gain (Loss) [Line Items]
Expenditures of turnarounds, capitalization period		2 years
Minimum | Land improvements
Derivative Instruments, Gain (Loss) [Line Items]
Property, plant and equipment, useful life		15 years
Minimum | Buildings
Derivative Instruments, Gain (Loss) [Line Items]
Property, plant and equipment, useful life		20 years
Minimum | Machinery and equipment
Derivative Instruments, Gain (Loss) [Line Items]
Property, plant and equipment, useful life		5 years
Minimum | Office equipment and other
Derivative Instruments, Gain (Loss) [Line Items]
Property, plant and equipment, useful life		3 years
Maximum | Major Maintenance Activities
Derivative Instruments, Gain (Loss) [Line Items]
Expenditures of turnarounds, capitalization period		4 years
Maximum | Other Intangible Assets
Derivative Instruments, Gain (Loss) [Line Items]
Expenditures of turnarounds, capitalization period		30 years
Maximum | Land improvements
Derivative Instruments, Gain (Loss) [Line Items]
Property, plant and equipment, useful life		20 years
Maximum | Buildings
Derivative Instruments, Gain (Loss) [Line Items]
Property, plant and equipment, useful life		40 years
Maximum | Machinery and equipment
Derivative Instruments, Gain (Loss) [Line Items]
Property, plant and equipment, useful life		20 years
Maximum | Office equipment and other
Derivative Instruments, Gain (Loss) [Line Items]
Property, plant and equipment, useful life		10 years