Condensed Consolidated Income Statements Statement (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2012	Mar. 31, 2011
Revenues:
Sales of physical commodities	$ 16,861.6	$ 14,506.4	$ 34,037.5	$ 30,715.2
Trading gains	38.0	30.9	111.4	47.9
Commission and clearing fees	41.5	36.9	73.5	74.5
Consulting and management fees	7.3	5.5	13.5	10.0
Interest income	2.3	3.0	5.0	5.5
Other income	0.3	0.3	0.5	0.7
Total revenues	16,951.0	14,583.0	34,241.4	30,853.8
Cost of sales of physical commodities	16,831.4	14,470.0	34,025.5	30,644.1
Operating revenues	119.6	113.0	215.9	209.7
Interest expense	3.6	3.3	5.7	7.1
Net revenues	116.0	109.7	210.2	202.6
Non-interest expenses:
Compensation and benefits	55.1	43.1	100.9	85.6
Clearing and related expenses	27.1	20.2	49.8	40.4
Introducing broker commissions	8.0	6.0	13.8	11.4
Communication and data services	5.6	3.4	10.2	6.9
Occupancy and equipment rental	2.7	2.2	5.5	4.0
Professional fees	3.6	1.9	6.3	4.0
Depreciation and amortization	1.9	1.1	3.4	2.1
Bad debts and impairments	(0.1)	2.1	0	4.5
Other	8.5	6.4	17.4	14.5
Total non-interest expenses	112.4	86.4	207.3	173.4
(Loss) income from continuing operations, before tax	3.6	23.3	2.9	29.2
Income tax (benefit) expense	1.2	8.0	1.0	10.1
Net (loss) income from continuing operations	2.4	15.3	1.9	19.1
Income from discontinued operations, net of tax	0	0	0	0.2
Net (loss) income	2.4	15.3	1.9	19.3
Add: Net loss attributable to noncontrolling interests	0	0.1	0.1	0.1
Net (loss) income attributable to INTL FCStone Inc. common stockholders	2.4	15.4	2.0	19.4
Basic (loss) earnings per share:
(Loss) income from continuing operations attributable to INTL FCStone Inc. common stockholders	$ 0.13	$ 0.87	$ 0.11	$ 1.09
Income from discontinued operations attributable to INTL FCStone Inc. common stockholders	$ 0.00	$ 0.00	$ 0.00	$ 0.01
Net (loss) income attributable to INTL FCStone Inc. common stockholders	$ 0.13	$ 0.87	$ 0.11	$ 1.1
Diluted (loss) earnings per share:
(Loss) income from continuing operations attributable to INTL FCStone Inc. common stockholders	$ 0.12	$ 0.81	$ 0.1	$ 1.02
Income from discontinued operations attributable to INTL FCStone Inc. common stockholders	$ 0.00	$ 0.00	$ 0.00	$ 0.01
Net (loss) income attributable to INTL FCStone Inc. common stockholders	$ 0.12	$ 0.81	$ 0.1	$ 1.03
Weighted-average number of common shares outstanding:
Basic	18,303,968	17,830,888	18,233,340	17,622,306
Diluted	19,187,360	19,224,588	19,167,927	19,181,158
Amounts attributable to INTL FCStone Inc. common stockholders:
(Loss) income from continuing operations, net of tax	2.4	15.4	2.0	19.2
Income (loss) from discontinued operations, net of tax	0	0	0	0.2
Net (loss) income	$ 2.4	$ 15.4	$ 2.0	$ 19.4