v3.26.1
Earnings Per Share (Net Income Attributable To CME Group) (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Millions
3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Earnings Per Share [Abstract]    
Dividends, Preferred Stock $ 0.0 $ (5.7)
Undistributed Earnings (Loss) Allocated to Participating Securities, Basic 13.7 0.0
Undistributed Earnings (Loss) Available to Common Shareholders, Basic 0.0 (6.3)
Net Income (Loss) Available to Common Stockholders, Basic 1,168.0 944.2
Overdistributed earnings allocated to preferred stock [Abstract] (13.7) 0.0
Net Income (Loss) from Continuing Operations Available to Common Shareholders, Diluted $ 1,154.3 $ 944.2
Basic (in shares) 359,318 359,613
Effect of stock options, restricted stock and performance shares 682 614
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Preferred Stock 3,208 0
Diluted (in shares) 363,208 360,227
Earnings per common share, basic (in dollars per share) $ 3.25 $ 2.63
Earnings per common share, diluted (in dollars per share) $ 3.18 $ 2.62