INVESTMENTS - Other Equity Investments (Details) - Investment in OCC - USD ($) $ in Millions			6 Months Ended
Mar. 03, 2015	Feb. 26, 2015	Jun. 30, 2018
Other Equity Investments
Percentage of equity securities			20.00%
Contribution requirement		$ 150
Contribution requirement, shareholder cap		$ 40
Customer refunds, percent of pre-tax income exceeding capital requirements		50.00%
Contributions	$ 30

Cost Method Investments, Customer Refunds, Percentage of Pre-tax Income Exceeding Capital Requirements

No definition available.

Name:	cboe_CostMethodInvestmentsCustomerRefundsPercentageofPretaxIncomeExceedingCapitalRequirements
Namespace Prefix:	cboe_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Cost Method Investments, Pro-rata Share of Ownership, Contribution Requirement

+ References

No definition available.

+ Details

Name:	cboe_CostMethodInvestmentsProrataShareofOwnershipContributionRequirement
Namespace Prefix:	cboe_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Cost Method Investments, Pro-rata Share of Ownership, Contribution Requirement, Shareholder Cap

+ References

No definition available.

+ Details

Name:	cboe_CostMethodInvestmentsProrataShareofOwnershipContributionRequirementShareholderCap
Namespace Prefix:	cboe_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The percentage of equity investment securities.

+ References

No definition available.

+ Details

Name:	cboe_EquityInvestmentSecuritiesPercentage
Namespace Prefix:	cboe_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The cash outflow associated with the purchase of all investments (debt, security, other) during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3213-108585

+ Details

Name:	us-gaap_PaymentsToAcquireInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

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.

+ References

No definition available.

+ Details

Name:	us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=cboe_OptionsClearingCorporationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: