XML 88 R1.htm IDEA: XBRL DOCUMENT v2.4.0.8
DEI Statement (USD $)
In Billions, except Share data, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Jun. 30, 2013
Feb. 12, 2014
Class B Common Stock, Class B1 [Member]
Feb. 12, 2014
Class B Common Stock, Class B2 [Member]
Feb. 12, 2014
Class B Common Stock, Class B3 [Member]
Feb. 12, 2014
Class B Common Stock, Class B4 [Member]
Feb. 12, 2014
Class A Common Stock (Shares) [Member]
Entity Information [Line Items]              
Entity Registrant Name CME GROUP INC.            
Entity Central Index Key 0001156375            
Current Fiscal Year End Date --12-31            
Entity Filer Category Large Accelerated Filer            
Document Type 10-K            
Document Period End Date Dec. 31, 2013            
Document Fiscal Year Focus 2013            
Document Fiscal Period Focus FY            
Amendment Flag false            
Entity Common Stock, Shares Outstanding     625 813 1,287 413 335,694,719
Entity Well-known Seasoned Issuer Yes            
Entity Voluntary Filers No            
Entity Current Reporting Status Yes            
Entity Public Float   $ 25.1