REGULATORY CAPITAL (Details) $ in Millions	9 Months Ended
	Sep. 30, 2019 USD ($)
Cboe Trading
Regulatory Requirement
Minimum net capital required to be maintained, option 1 - percentage of aggregate indebtedness items	6.67%
Minimum net capital required to be maintained, option 2 - amount	$ 0.1
Net capital	11.8
Excess net capital	11.4
Required net capital	0.4
Cboe Europe Equities
Regulatory Requirement
Financial resources requirement	20.3
Capital in excess of financial resources requirement	34.2
Cboe Chi-X Europe
Regulatory Requirement
Capital resources requirement	0.1
Capital in excess of capital resources requirement	0.5
Cboe Europe B.V
Regulatory Requirement
Capital in excess of financial resources requirement	2.9
Minimum capital requirement	1.8
Cboe SEF
Regulatory Requirement
Annual operating expenses for swap execution facility capital adequacy tests	0.7
XX month operating expenses for swap execution facility capital adequacy tests	0.4
CFE
Regulatory Requirement
Annual operating expenses for registered futures exchange capital adequacy tests	55.3
XX month operating expenses for registered futures exchange capital adequacy tests	$ 27.7