Derivative Financial Instruments and Hedging Activities - Fair Value of Commodity Derivative Instruments (Details) - USD ($) $ in Thousands |
May 31, 2021 |
Aug. 31, 2020 |
|---|---|---|
| Derivatives, Fair Value [Line Items] | ||
| Derivative Liability, Fair Value, Gross Liability | $ 595,565 | $ 412,809 |
| Derivative Asset, Fair Value, Gross Asset | 889,233 | 358,300 |
| Cash Flow Hedging | Designated as Hedging Instrument | ||
| Derivatives, Fair Value [Line Items] | ||
| Derivative Liability, Fair Value, Gross Liability | 6,761 | 8,821 |
| Derivative Asset, Fair Value, Gross Asset | $ 11,243 | $ 34,052 |