Cover - shares	9 Months Ended
	Sep. 30, 2022	Oct. 12, 2022
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2022
Document Transition Report	false
Entity File Number	001-31553
Entity Registrant Name	CME GROUP INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	36-4459170
Entity Address, Street Address	20 South Wacker Drive
Entity Address, City	Chicago
Entity Address, State	IL
Entity Address, Postal Zip Code	60606
City Area Code	312
Local Phone Number	930-1000
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Title of each class	Class A Common Stock
Trading symbol	CME
Name of each exchange on which registered	NASDAQ
Document Fiscal Period Focus	Q3
Document Fiscal Year Focus	2022
Current Fiscal Year End Date	--12-31
Entity Central Index Key	0001156375
Amendment Flag	false
Class A Common Stock [Member]
Entity Common Stock, Shares Outstanding		359,724,979
Class B Common Stock, Class B-1 [Member]
Entity Common Stock, Shares Outstanding		625
Class B Common Stock, Class B-2 [Member]
Entity Common Stock, Shares Outstanding		813
Class B Common Stock, Class B-3 [Member]
Entity Common Stock, Shares Outstanding		1,287
Class B Common Stock, Class B-4 [Member]
Entity Common Stock, Shares Outstanding		413