Related Party Transactions (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions					1 Months Ended		3 Months Ended			4 Months Ended	12 Months Ended
	Jul. 31, 2014	Jun. 25, 2014	Jul. 25, 2013	Apr. 02, 2013	Dec. 31, 2015	Dec. 31, 2013	Jun. 30, 2014	Dec. 31, 2013	Mar. 31, 2013	Jul. 25, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Jun. 30, 2012
Related Party Transaction [Line Items]
Total number of shares purchased (in shares)			0.7	1.4	0.3				7.2	9.3
Total cash utilized					$ 26						$ 1,002	$ 346	$ 989
Average price paid per share (in dollars per share)					$ 98.98	$ 58.36					$ 99.00	$ 79.06	$ 58.52
Other (Income) Loss [Member]
Related Party Transaction [Line Items]
Non-cash impairment charge								$ 36
Harold W. McGraw III [Member]
Related Party Transaction [Line Items]
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 [Member] | S&P/DJ Indices [Member]
Related Party Transaction [Line Items]
Revenues earned under license agreement											$ 63	$ 52	$ 46
Noncontrolling interest ownership by noncontrolling owners														27.00%
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | Other (Income) Loss [Member]
Related Party Transaction [Line Items]
Non-cash impairment charge							$ 6
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | Harold W. McGraw III [Member]
Related Party Transaction [Line Items]
Amount of transaction with related party	$ 20