Derivative Financial Instruments and Hedging Activities - Pretax Gains (Losses) Recorded in Other Comprehensive Income Relating to Cash Flow Hedges (Details) - USD ($) $ in Thousands	12 Months Ended
Aug. 31, 2019	Aug. 31, 2018	Aug. 31, 2017
Cash Flow Hedging [Member] \| Commodity [Member]
Derivative [Line Items]
Other Comprehensive Income (Loss), Derivative, Excluded Component, Increase (Decrease), after Adjustments and Tax	$ 27,650	$ 178	$ 0

Amount, after tax and adjustments, of gain (loss) from increase (decrease) in value of excluded component of derivative designated and qualifying as hedge. Adjustments include, but are not limited to, reclassifications for sale and settlement, and amounts recognized under systematic and rational method.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (bb)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624171-113959

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (dd)
-URI http://asc.fasb.org/extlink&oid=118930883&loc=SL7669646-108580

Name:	us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseAfterAdjustmentsAndTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration