EMPLOYEE BENEFITS (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
SMART Plan
Defined Contribution Plan
Company contribution amount	$ 3.3	$ 2.7	$ 8.5	$ 6.7
Balance amount in the plan			20.9
Cboe Europe Equities Employee Selected Stakeholder Contribution Plan
Defined Contribution Plan
Company contribution amount	$ 0.2	$ 0.3	$ 0.5	$ 0.6