Fair Value Measurements - Fair Value Measurements (Details) - Fair Value, Recurring [Member] - USD ($) $ in Thousands	Nov. 30, 2022	Aug. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred compensation assets	$ 48,430	$ 46,562
Securities Segregated under Other Regulations	207,521	238,124
Other assets	85,457	11,718
Total assets	720,551	840,648
Foreign exchange derivatives		12,649
Total liabilities	266,178	402,788
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	48,430	46,562
Securities Segregated under Other Regulations	207,521	238,124
Other assets	85,457	11,718
Total assets	342,110	297,565
Foreign exchange derivatives		0
Total liabilities	2,894	10,256
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred compensation assets	0	0
Securities Segregated under Other Regulations	0	0
Other assets	0	0
Total assets	378,441	543,083
Foreign exchange derivatives		12,649
Total liabilities	263,284	392,532
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred compensation assets	0	0
Securities Segregated under Other Regulations	0	0
Other assets	0	0
Total assets	0	0
Foreign exchange derivatives		0
Total liabilities	0	0
Commodity derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	327,634	491,321
Derivative Liability	252,241	390,139
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	702	1,161
Derivative Liability	2,894	10,256
Commodity derivatives | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	326,932	490,160
Derivative Liability	249,347	379,883
Commodity derivatives | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	0	0
Derivative Liability	0	0
Foreign exchange derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign exchange derivatives	51,509	52,923
Foreign exchange derivatives	13,937
Foreign exchange 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 exchange derivatives	0	0
Foreign exchange derivatives	0
Foreign exchange derivatives | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign exchange derivatives	51,509	52,923
Foreign exchange derivatives	13,937
Foreign exchange derivatives | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign exchange derivatives	0	$ 0
Foreign exchange derivatives	$ 0