Segment Analysis (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Sep. 30, 2015
Segment Reporting Information [Line Items]
Revenues	$ 4,868.5	$ 3,995.1	$ 11,977.3	$ 32,064.8
Operating revenues	175.0	151.6	492.4	445.6
Net operating revenues	117.3	103.4	332.9	304.5
Net Segment Contribution	87.4	77.9	254.3	231.5
Segment Income	54.4	45.4	152.5	135.4
Costs not allocated to operating segments	33.0	28.2	99.0	86.5
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest	21.4	17.2	53.5	48.9
Assets	6,065.9		6,065.9		$ 5,070.0
Commercial Hedging [Member]
Segment Reporting Information [Line Items]
Revenues	71.9	62.2	182.0	195.3
Operating revenues	71.9	62.2	182.0	195.3
Net operating revenues	57.7	50.3	145.6	161.0
Net Segment Contribution	41.4	34.5	103.6	114.4
Segment Income	25.4	18.7	54.2	65.3
Assets	1,685.3		1,685.3		1,548.1
Global Payments [Member]
Segment Reporting Information [Line Items]
Revenues	18.4	18.2	54.1	51.8
Operating revenues	18.4	18.2	54.1	51.8
Net operating revenues	16.4	16.3	48.2	45.9
Net Segment Contribution	13.2	13.0	38.6	36.6
Segment Income	9.9	10.2	29.2	28.3
Assets	210.1		210.1		207.3
Securities Segment [Member]
Segment Reporting Information [Line Items]
Revenues	41.6	36.5	136.0	89.8
Operating revenues	41.6	36.5	136.0	89.8
Net operating revenues	27.7	25.3	95.5	60.8
Net Segment Contribution	21.2	20.2	75.7	46.4
Segment Income	14.4	12.8	54.5	26.7
Assets	2,452.3		2,452.3		1,861.0
Physical Commodities [Member]
Segment Reporting Information [Line Items]
Revenues	4,701.2	3,847.6	11,506.4	31,636.2
Operating revenues	7.7	4.1	21.5	17.0
Net operating revenues	6.2	3.8	17.7	15.3
Net Segment Contribution	3.6	3.2	12.3	12.1
Segment Income	1.3	0.9	4.2	5.8
Assets	270.8		270.8		190.9
Clearing and Execution Services Segment [Member]
Segment Reporting Information [Line Items]
Revenues	33.3	29.5	96.4	92.2
Operating revenues	33.3	29.5	96.4	92.2
Net operating revenues	10.0	9.0	30.8	27.7
Net Segment Contribution	8.0	7.0	24.1	22.0
Segment Income	3.4	2.8	10.4	9.3
Assets	1,266.4		1,266.4		1,163.8
Corporate [Member]
Segment Reporting Information [Line Items]
Revenues	2.1	1.1	2.4	(0.5)
Operating revenues	2.1	1.1	2.4	(0.5)
Net operating revenues	(0.7)	$ (1.3)	(4.9)	$ (6.2)
Assets	$ 181.0		$ 181.0		$ 98.9

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Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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-SubTopic 10
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