Fair Value Measurements (Tables)
 9 Months Ended
May 31, 2021
Fair Value Disclosures [Abstract]  
Fair Value Measurements, Recurring and Nonrecurring
May 31, 2021
Quoted Prices in
Active Markets
for Identical
Assets
(Level 1)		Significant
Other
Observable
Inputs
(Level 2)		Significant
Unobservable
Inputs
(Level 3)		Total
(Dollars in thousands)
Assets    
Commodity derivatives$2,349 $852,622 $— $854,971 
Foreign exchange derivatives— 29,332 — 29,332 
Deferred compensation assets50,660 — — 50,660 
Embedded derivative asset— 16,173 — 16,173 
Segregated investments and marketable securities195,197 — — 195,197 
Other assets6,563 — — 6,563 
Total$254,769 $898,127 $— $1,152,896 
Liabilities    
Commodity derivatives$1,037 $591,382 $— $592,419 
Foreign exchange derivatives— 9,907 — 9,907 
Total$1,037 $601,289 $— $602,326 
August 31, 2020
Quoted Prices in
Active Markets
for Identical
Assets
(Level 1)		Significant
Other
Observable
Inputs
(Level 2)		Significant
Unobservable
Inputs
(Level 3)		Total
(Dollars in thousands)
Assets
Commodity derivatives$5,762 $355,783 $— $361,545 
Foreign exchange derivatives— 11,523 — 11,523 
Deferred compensation assets47,669 — — 47,669 
Embedded derivative asset— 18,998 — 18,998 
Segregated investments and marketable securities85,950 — — 85,950 
Other assets5,276 — — 5,276 
Total$144,657 $386,304 $— $530,961 
Liabilities
Commodity derivatives$6,037 $346,126 $— $352,163 
Foreign exchange derivatives— 69,467 — 69,467 
Total$6,037 $415,593 $— $421,630