Derivative Financial Instruments and Hedging Activities - Gross Fair Values of Derivative Assets, Derivative Liabilities, and Margin Deposits (Cash Collateral) (Details) - USD ($) $ in Thousands	Nov. 30, 2021	Aug. 31, 2021
Reconciliation of gross and net fair value of assets and liabilities subject to offsetting arrangements [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 467,315	$ 568,749
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	459,641	558,993
Derivative Liability, Fair Value, Gross Liability	321,092	453,367
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	311,272	441,126
Not Designated as Hedging Instrument | Commodity derivatives
Reconciliation of gross and net fair value of assets and liabilities subject to offsetting arrangements [Line Items]
Derivative Asset, Fair Value, Gross Asset	445,798	532,832
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	442,169	528,658
Derivative Liability, Fair Value, Gross Liability	293,629	444,861
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	287,854	438,202
Not Designated as Hedging Instrument | Foreign exchange derivatives
Reconciliation of gross and net fair value of assets and liabilities subject to offsetting arrangements [Line Items]
Derivative Asset, Fair Value, Gross Asset	8,483	19,429
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	4,438	13,847
Derivative Liability, Fair Value, Gross Liability	27,463	8,506
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	23,418	2,924
Not Designated as Hedging Instrument | Embedded Derivative Financial Instruments [Member]
Reconciliation of gross and net fair value of assets and liabilities subject to offsetting arrangements [Line Items]
Derivative Asset, Fair Value, Gross Asset	13,034	16,488
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	$ 13,034	$ 16,488