Fair Value Measurements - Recurring Fair Value Measurements (Details) - USD ($) $ in Thousands	Aug. 31, 2018	Aug. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Embedded Derivative, Fair Value of Embedded Derivative Asset	$ 23,600
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred Compensation Assets, at Fair Value	39,073	$ 52,414
Deferred Consideration Receivable, Fair Value Disclosure		548,602
Embedded Derivative, Fair Value of Embedded Derivative Asset	23,595	25,533
Other assets	5,334	14,846
Total assets	397,249	875,501
Total liabilities	455,842	313,968
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred Compensation Assets, at Fair Value	39,073	52,414
Deferred Consideration Receivable, Fair Value Disclosure		0
Embedded Derivative, Fair Value of Embedded Derivative Asset	0	0
Other assets	5,334	14,846
Total assets	98,894	115,743
Total liabilities	31,778	31,190
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred Compensation Assets, at Fair Value	0	0
Deferred Consideration Receivable, Fair Value Disclosure		0
Embedded Derivative, Fair Value of Embedded Derivative Asset	23,595	25,533
Other assets	0	0
Total assets	298,355	211,156
Total liabilities	424,064	282,778
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred Compensation Assets, at Fair Value	0	0
Deferred Consideration Receivable, Fair Value Disclosure		548,602
Embedded Derivative, Fair Value of Embedded Derivative Asset	0	0
Other assets	0	0
Total assets	0	548,602
Total liabilities	0	0
Fair Value, Measurements, Recurring | Commodity derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	313,846	215,349
Derivative Liability	421,689	293,330
Fair Value, Measurements, Recurring | Commodity derivatives | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	54,487	48,483
Derivative Liability	31,778	31,190
Fair Value, Measurements, Recurring | Commodity derivatives | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	259,359	166,866
Derivative Liability	389,911	262,140
Fair Value, Measurements, Recurring | Commodity derivatives | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	0	0
Derivative Liability	0	0
Fair Value, Measurements, Recurring | Foreign currency derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign Currency Contract, Asset, Fair Value Disclosure	15,401	8,779
Foreign Currency Contracts, Liability, Fair Value Disclosure	24,701	19,931
Fair Value, Measurements, Recurring | Foreign currency derivatives | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign Currency Contract, Asset, Fair Value Disclosure	0	0
Foreign Currency Contracts, Liability, Fair Value Disclosure	0	0
Fair Value, Measurements, Recurring | Foreign currency derivatives | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign Currency Contract, Asset, Fair Value Disclosure	15,401	8,779
Foreign Currency Contracts, Liability, Fair Value Disclosure	24,701	19,931
Fair Value, Measurements, Recurring | Foreign currency derivatives | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign Currency Contract, Asset, Fair Value Disclosure	0	0
Foreign Currency Contracts, Liability, Fair Value Disclosure	0	0
Fair Value, Measurements, Recurring | Interest rate swap derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset		9,978
Derivative Liability	9,452	707
Fair Value, Measurements, Recurring | Interest rate swap derivatives | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset		0
Derivative Liability	0	0
Fair Value, Measurements, Recurring | Interest rate swap derivatives | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset		9,978
Derivative Liability	9,452	707
Fair Value, Measurements, Recurring | Interest rate swap derivatives | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset		0
Derivative Liability	$ 0	$ 0