Earnings Per Share (Tables)

9 Months Ended

Sep. 30, 2012

Earnings Per Share [Abstract]

Basic And Diluted Earnings Per Share

	Quarter Ended September 30,				Nine Months Ended September 30,
	2012		2011		2012		2011
Net Income Attributable to CME Group (in millions)	$	218.0	$	316.1	$	729.5	$	1,066.4
Weighted Average Number of Common Shares (in thousands):
Basic	331,377		332,289		331,091		333,449
Effect of stock options and restricted stock awards	1,081		1,048		1,056		1,058
Diluted	332,458		333,337		332,147		334,507
Earnings per Common Share Attributable to CME Group:
Basic	$	0.66	$	0.95	$	2.20	$	3.20
Diluted	0.66		0.95		2.20		3.19