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Net segment contribution equals revenues less cost of sales, transaction-based clearing expenses, variable bonus compensation, introducing broker commissions and interest expense.

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Segment Income equals net contribution less non-variable direct segment costs.

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No definition available.

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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(12))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(11))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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Aggregate revenue less cost of goods and services sold or operating expenses directly attributable to the revenue generation activity.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1,2)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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Amount of income (loss) from continuing operations before deduction of income tax expense (benefit) and income (loss) attributable to noncontrolling interest, and addition of income (loss) from equity method investments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(h)(1)(i))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income after deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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Segment and Geographic Information (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Segment Reporting Information [Line Items]
Revenues	$ 12,382.5	$ 5,505.9	$ 5,460.8	$ 6,074.4	$ 2,777.6	$ 4,868.5	$ 3,708.9	$ 3,399.9	$ 29,423.6	$ 14,754.9	$ 34,693.2
Operating revenues	205.1	197.6	195.8	185.5	178.6	175.0	166.1	151.3	784.0	671.0	624.3
Revenues, Net of Interest Expense	131.1	123.3	123.9	114.3	111.0	117.3	112.9	102.7	492.6	443.9	431.8
Net Segment Contribution									387.0	347.0	320.6
Segment Income									169.0	206.0	188.1
Costs not allocated to operating segments									153.8	133.3	110.0
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	(22.5)	$ 15.0	$ 14.3	$ 8.4	19.2	$ 21.4	$ 20.0	$ 12.1	15.2	72.7	78.1
Assets	6,243.4				5,950.3				6,243.4	5,950.3	5,070.0
Commercial Hedging [Member]
Segment Reporting Information [Line Items]
Revenues									244.6	236.1	262.4
Operating revenues									244.6	236.1	262.4
Revenues, Net of Interest Expense									194.3	188.2	214.7
Net Segment Contribution									141.8	134.4	151.7
Segment Income									72.8	68.7	85.6
Assets	1,650.3				1,637.5				1,650.3	1,637.5	1,548.1
Global Payments [Member]
Segment Reporting Information [Line Items]
Revenues									89.2	73.2	77.1
Operating revenues									89.2	73.2	77.1
Revenues, Net of Interest Expense									80.6	65.3	68.5
Net Segment Contribution									64.4	52.2	54.5
Segment Income									50.6	39.8	43.3
Assets	199.5				191.4				199.5	191.4	207.3
Securities Segment [Member]
Segment Reporting Information [Line Items]
Revenues									151.7	175.2	129.8
Operating revenues									151.7	175.2	129.8
Revenues, Net of Interest Expense									94.6	121.9	88.6
Net Segment Contribution									75.6	97.5	67.4
Segment Income									46.6	69.4	40.5
Assets	2,101.7				2,130.7				2,101.7	2,130.7	1,861.0
Physical Commodities Segment [Member]
Segment Reporting Information [Line Items]
Revenues									28,684.4	14,120.5	34,092.0
Operating revenues									44.8	36.6	23.1
Revenues, Net of Interest Expense									37.3	31.5	21.2
Net Segment Contribution									27.2	23.4	16.9
Segment Income									(31.4)	13.3	5.8
Assets	339.5				258.0				339.5	258.0	190.9
Clearing and Execution Services Segment [Member]
Segment Reporting Information [Line Items]
Revenues									259.8	151.1	123.4
Operating revenues									259.8	151.1	123.4
Revenues, Net of Interest Expense									102.2	48.8	38.3
Net Segment Contribution									78.0	39.5	30.1
Segment Income									30.4	14.8	12.9
Assets	1,818.9				1,617.4				1,818.9	1,617.4	1,163.8
Corporate [Member]
Segment Reporting Information [Line Items]
Revenues									(6.1)	(1.2)	8.5
Operating revenues									(6.1)	(1.2)	8.5
Revenues, Net of Interest Expense									(16.4)	(11.8)	0.5
Assets	$ 133.5				$ 115.3				$ 133.5	$ 115.3	$ 98.9