ACQUISITIONS - Pro forma financial information (Details) - Bats Global Markets, Inc. $ / shares in Units, $ in Millions	6 Months Ended
Jun. 30, 2017 USD ($) $ / shares
Acquisitions
Revenue	$ 1,269.9
Revenue less cost of revenues	532.2
Operating income	229.4
Net income	$ 157.3
Earnings per share:
Basic (in dollars per share) \| $ / shares	$ 1.40
Diluted (in dollars per share) \| $ / shares	$ 1.40

Business Acquisition, Pro Forma Operating Income (Loss)

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The pro forma gross profit for a period as if the business combination or combinations had been completed at the beginning of the period.

+ References

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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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Per basic share amount of pro forma income from continuing operations, after tax, as if the business combination had been completed at the beginning of a period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(2)-(3)
-URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

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Per diluted share amount of pro forma income from continuing operations, after tax, as if the business combination had been completed at the beginning of a period.

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The pro forma net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period.

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The pro forma revenue for a period as if the business combination or combinations had been completed at the beginning of the period.

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