v3.26.1
Earnings Per Share (Schedule of Earnings Per Share Calculation) (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Earnings Per Share [Abstract]        
Net Income $ 1,041.8 $ 1,025.1 $ 2,196.1 $ 1,981.3
Less: preferred stock dividends 0.0 (5.7) 0.0 (11.5)
Add: overdistributed earnings allocated to preferred stock 0.0 0.0 4.3 0.0
Less: undistributed earnings allocated to preferred stock 0.0 (7.2) 0.0 (13.4)
Net Income Attributable to Common Shareholders of CME Group - Basic 1,041.8 1,012.2 2,200.4 1,956.4
Less: overdistributed earnings allocated to preferred stock 0.0 0.0 (4.3) 0.0
Net Income Attributable to Common Shareholders of CME Group - Diluted $ 1,041.8 $ 1,012.2 $ 2,196.1 $ 1,956.4
Weighted Average Number of Common Shares:        
Basic (in shares) 360,684 359,658 360,005 359,636
Effect of restricted stock and performance shares (in shares) 598 697 632 661
Effect of convertible preferred shares (in shares) 0 0 1,596 0
Diluted (in shares) 361,282 360,355 362,233 360,297
Earnings per Common Share Attributable to Common Shareholders of CME Group:        
Earnings per common share, basic (in dollars per share) $ 2.89 $ 2.81 $ 6.11 $ 5.44
Earnings per common share, diluted (in dollars per share) $ 2.88 $ 2.81 $ 6.06 $ 5.43