Earnings Per Share (Details) (USD $) In Millions, except Per Share data	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Amounts attributable to The McGraw-Hill Companies, Inc. common shareholders:
Income from continuing operations	$ 366.7	$ 379.2	$ 698.3	$ 673.3
Loss from discontinued operations, net of tax	(1.1)	0.7	(1.7)	0.9
Net income attributable to the Company	$ 365.6	$ 379.9	$ 696.6	$ 674.2
Basic weighted-average number of common shares outstanding	297.8	307.2	302.2	310.6
Effect of stock options and other dilutive securities	5.8	2.1	5.2	2.3
Diluted weighted-average number of common shares outstanding	303.6	309.3	307.4	312.9
Basic EPS:
Income from continuing operations	$ 1.23	$ 1.23	$ 2.31	$ 2.17
Loss from discontinued operations, net of tax	$ 0	$ 0.01	$ 0	$ 0
Net income	$ 1.23	$ 1.24	$ 2.31	$ 2.17
Diluted EPS:
Income from continuing operations	$ 1.21	$ 1.23	$ 2.27	$ 2.15
Loss from discontinued operations, net of tax	$ 0	$ 0	$ 0	$ 0
Net income	$ 1.21	$ 1.23	$ 2.27	$ 2.15
Restricted Stock [Member]
Common Shares Outstanding (Textuals) [Abstract]
Outstanding shares not included in the computation of diluted earnings per share for both restricted stock and stock options			1.6	3.2
Stock Options [Member]
Common Shares Outstanding (Textuals) [Abstract]
Outstanding shares not included in the computation of diluted earnings per share for both restricted stock and stock options	9.9	24.4	10.2	23.9