Fair Value Measurements - Recurring Fair Value Measurements (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Aug. 31, 2025	Aug. 31, 2024
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities Segregated under Other Regulations	$ 169,978	$ 151,327
Deposits, Fair Value Disclosure		500,921
Other assets	110,532	83,008
Total assets	459,725	915,220
Total liabilities	179,679	249,060
Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities Segregated under Other Regulations	0	0
Deposits, Fair Value Disclosure		0
Other assets	0	0
Total assets	0	0
Total liabilities	0	0
Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities Segregated under Other Regulations	135,675	136,258
Deposits, Fair Value Disclosure		500,921
Other assets	0	0
Total assets	311,737	814,689
Total liabilities	178,569	247,419
Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities Segregated under Other Regulations	34,303	15,069
Deposits, Fair Value Disclosure		0
Other assets	110,532	83,008
Total assets	147,988	100,531
Total liabilities	1,110	1,641
Commodity derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Instruments and Hedges, Liabilities	167,908	224,584
Derivative Instruments and Hedges, Assets	135,688	170,935
Commodity derivatives | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Instruments and Hedges, Liabilities	0	0
Derivative Instruments and Hedges, Assets	0	0
Commodity derivatives | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Instruments and Hedges, Liabilities	166,798	222,943
Derivative Instruments and Hedges, Assets	132,535	168,481
Commodity derivatives | Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Instruments and Hedges, Liabilities	1,110	1,641
Derivative Instruments and Hedges, Assets	3,153	2,454
Foreign exchange derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign Currency Contract, Asset, Fair Value Disclosure	43,527	9,029
Foreign Currency Contracts, Liability, Fair Value Disclosure	11,771	24,476
Foreign exchange derivatives | Fair Value, 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
Foreign exchange derivatives | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign Currency Contract, Asset, Fair Value Disclosure	43,527	9,029
Foreign Currency Contracts, Liability, Fair Value Disclosure	11,771	24,476
Foreign exchange derivatives | Fair Value, Inputs, 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