Related Party Transactions (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions			3 Months Ended			9 Months Ended
	Jul. 31, 2014	Jun. 25, 2014	Sep. 30, 2015	Sep. 30, 2014	Jun. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Related Party Transaction [Line Items]
Total number of shares purchased (in shares)			2.3	0.0		4.9	4.4
Total cash utilized						$ 505
Average price paid per share (in dollars per share)			$ 99.01	$ 0.00		$ 102.01	$ 79.06
Other (Income) Loss [Member]
Related Party Transaction [Line Items]
Non-cash impairment charge				$ 6	$ 6
Harold W. McGraw III [Member]
Related Party Transaction [Line Items]
Transaction amount	$ 20
Total number of shares purchased (in shares)		0.5
Repurchase discount		0.35%
Total cash utilized		$ 41
Average price paid per share (in dollars per share)		$ 82.66
CME Group | S&P DJ Indices
Related Party Transaction [Line Items]
Revenues earned under license agreement			$ 19			$ 47
Noncontrolling interest ownership by noncontrolling owners			27.00%			27.00%