Condensed Consolidated Income Statements - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Revenues:
Total revenues	$ 34,828.8	$ 27,069.7	$ 99,654.8	$ 68,748.8
Cost of sales of physical commodities	33,804.5	26,156.0	96,730.2	66,232.7
Operating revenues	1,024.3	913.7	2,924.6	2,516.1
Transaction-based clearing expenses	94.9	81.0	273.2	233.8
Introducing broker commissions	49.7	43.1	139.5	124.2
Interest expense	371.3	297.0	994.1	792.2
Interest expense on corporate funding	20.1	24.1	50.1	53.5
Net operating revenues	488.3	468.5	1,467.7	1,312.4
Compensation and other expenses:
Compensation and benefits	267.3	257.5	786.9	710.0
Trading systems and market information	21.3	20.1	60.8	58.2
Professional fees	23.9	20.0	59.4	55.0
Non-trading technology and support	21.1	18.7	61.7	53.6
Occupancy and equipment rental	14.3	13.5	40.4	34.8
Selling and marketing	13.0	12.8	38.4	40.1
Travel and business development	7.9	6.9	23.4	21.1
Communications	2.2	1.9	6.4	6.4
Depreciation and amortization	14.9	12.3	46.2	35.8
Bad debts (recoveries), net	0.4	0.5	2.3	(0.2)
Other	15.1	18.1	46.6	50.3
Total compensation and other expenses	401.4	382.3	1,172.5	1,065.1
Other (loss) gains, net	(1.3)	1.8	4.4	8.7
Income before tax	85.6	88.0	299.6	256.0
Income tax expense	22.2	26.1	79.4	71.9
Net income	$ 63.4	$ 61.9	$ 220.2	$ 184.1
Earnings per share:
Basic (in dollars per share)	$ 1.29	$ 1.30	$ 4.55	$ 3.89
Diluted (in dollars per share)	$ 1.22	$ 1.25	$ 4.32	$ 3.76
Weighted-average number of common shares outstanding:
Basic (in shares)	47,115,819	45,964,905	46,773,656	45,673,929
Diluted (in shares)	49,952,164	47,614,548	49,302,730	47,231,055
Sales of physical commodities
Revenues:
Total revenues	$ 33,839.9	$ 26,196.2	$ 96,883.6	$ 66,339.0
Principal gains, net
Revenues:
Total revenues	334.0	305.6	943.4	881.2
Commission and clearing fees
Revenues:
Total revenues	166.0	143.0	479.6	408.9
Consulting, management, and account fees
Revenues:
Total revenues	46.2	45.3	138.3	124.0
Interest income
Revenues:
Total revenues	$ 442.7	$ 379.6	$ 1,209.9	$ 995.7