Acquisitions and Divestitures (Narrative) (Details) (USD $)	1 Months Ended	3 Months Ended		0 Months Ended	3 Months Ended	12 Months Ended
	Mar. 31, 2014 Country company	Mar. 31, 2014	Mar. 31, 2013	Mar. 22, 2013 MHE	Mar. 31, 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
After-tax gain on sale of business		$ 0	$ 612,000,000		$ 612,000,000	$ 589,000,000
Cash proceeds from sale of business				$ 2,400,000,000