Leases (Details)	Jun. 30, 2020
Leases [Abstract]
Operating Lease, Weighted Average Remaining Lease Term	18
Lessee, Operating Lease, Renewal Term	5
Lessee, Operating Lease, Option to Terminate	12
Lessee, Operating Lease, Term of Contract	12

Operating Lease, Option to Early Terminate, Months

No definition available.

Name:	cme_OperatingLeaseOptiontoEarlyTerminateMonths
Namespace Prefix:	cme_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant