Acquisitions and Divestitures (Narrative) (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended		6 Months Ended		0 Months Ended			6 Months Ended	12 Months Ended
	Mar. 31, 2014 Country company	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 Data Center [Member] Other Current Assets [Member]	Jun. 30, 2014 Data Center [Member] Other Loss [Member]	Mar. 22, 2013 MHE	Jun. 30, 2013 MHE	Dec. 31, 2013 MHE
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Minimum Number of Companies Represented in Broad Market Indices	11,000
Minimum Number of Countries Represented in Broad Market Indices	52
Contingent consideration payment				$ 11	$ 12
After-tax gain (loss) on sale of business		0	0	0	612		(3)		612	589
Cash proceeds from sale of business						$ 58		$ 2,400