Condensed Consolidated Income Statements - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenues:
Sales of physical commodities	$ 9,785.9	$ 7,944.5	$ 29,473.7	$ 38,939.4
Principal gains, net	232.1	161.0	700.7	442.0
Commission and clearing fees	124.0	96.1	373.2	299.9
Consulting, management, and account fees	22.3	19.4	67.4	63.3
Interest income	27.8	22.4	72.4	110.1
Total revenues	10,192.1	8,243.4	30,687.4	39,854.7
Cost of sales of physical commodities	9,760.6	7,920.8	29,404.4	38,888.5
Operating revenues	431.5	322.6	1,283.0	966.2
Transaction-based clearing expenses	67.1	55.3	207.3	165.4
Introducing broker commissions	41.8	24.0	120.8	79.8
Interest expense	14.5	11.5	35.5	70.4
Interest expense on corporate funding	10.1	3.9	31.1	8.8
Net operating revenues	298.0	227.9	888.3	641.8
Compensation and other expenses:
Compensation and benefits	177.3	132.5	515.9	373.2
Trading systems and market information	14.4	11.8	42.9	33.4
Professional fees	9.5	6.1	27.8	16.8
Non-trading technology and support	11.3	6.9	32.8	18.8
Occupancy and equipment rental	9.7	5.4	25.8	15.3
Selling and marketing	8.1	0.5	23.4	6.1
Travel and business development	1.3	0.7	2.8	8.4
Communications	2.3	1.7	7.0	4.8
Depreciation and amortization	9.7	4.4	26.7	12.5
Bad debts	1.3	1.8	3.7	6.2
Other	10.7	7.1	33.9	19.6
Total compensation and other expenses	255.6	178.9	742.7	515.1
Gain on acquisitions and other gains	3.6	0.0	3.6	0.1
Income before tax	46.0	49.0	149.2	126.8
Income tax expense	11.8	12.4	40.2	34.6
Net income	$ 34.2	$ 36.6	$ 109.0	$ 92.2
Earnings per share:
Basic (in dollar per shares)	$ 1.72	$ 1.90	$ 5.53	$ 4.78
Diluted (in dollar per shares)	$ 1.67	$ 1.87	$ 5.38	$ 4.71
Weighted-average number of common shares outstanding:
Basic (in shares)	19,255,452	18,807,104	19,102,244	18,809,823
Diluted (in shares)	19,855,226	19,103,166	19,669,397	19,122,681