Derivative Financial Instruments and Hedging Activities - Gross Fair Values of Derivative Assets, Derivative Liabilities, and Margin Deposits (Cash Collateral) (Details) - USD ($) $ in Thousands	Feb. 28, 2022	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	$ 885,009	$ 568,749
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	867,675	558,993
Derivative Liability, Fair Value, Gross Liability	573,049	453,367
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	554,037	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	804,483	532,832
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	793,251	528,658
Derivative Liability, Fair Value, Gross Liability	566,818	444,861
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	553,908	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	67,239	19,429
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	61,137	13,847
Derivative Liability, Fair Value, Gross Liability	6,231	8,506
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	129	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	13,287	16,488
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	$ 13,287	$ 16,488