Earnings Per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Amount attributable to The McGraw-Hill Companies, Inc. common shareholders:
Income from continuing operations	$ 190	$ 151	$ 176	$ 158	$ 108	$ 161	$ 177	$ 160	$ 676	$ 607	$ 581
Loss from discontinued operations, net of tax	(406)	162	39	(35)	106	205	34	(40)	(239)	304	247
Net income attributable to The McGraw-Hill Companies, Inc.	$ (216)	$ 314	$ 216	$ 123	$ 214	$ 366	$ 211	$ 120	$ 437	$ 911	$ 828
Basic weighted-average number of common shares outstanding (in shares)									278.6	298.1	309.4
Effect of stock options and other dilutive securities (in shares)									6.0	5.5	2.8
Diluted weighted-average number of common shares outstanding (in shares)									284.6	303.6	312.2
Basic EPS:
Basic, Income from continuing operations (in usd per share)	$ 0.68	$ 0.54	$ 0.63	$ 0.57	$ 0.38	$ 0.54	$ 0.59	$ 0.52	$ 2.43	$ 2.03	$ 1.88
Basic, Income (loss) from discontinued operations, net of tax (in usd per share)	$ (1.46)	$ 0.58	$ 0.14	$ (0.13)	$ 0.37	$ 0.69	$ 0.11	$ (0.13)	$ (0.86)	$ 1.02	$ 0.80
Basic, Net income (in usd per share)	$ (0.78)	$ 1.13	$ 0.77	$ 0.44	$ 0.75	$ 1.23	$ 0.70	$ 0.39	$ 1.57	$ 3.05	$ 2.68
Diluted EPS:
Diluted, Income from continuing operations (in usd per share)	$ 0.67	$ 0.53	$ 0.62	$ 0.56	$ 0.37	$ 0.53	$ 0.57	$ 0.52	$ 2.37	$ 2.00	$ 1.86
Diluted, Income (loss) from discontinued operations, net of tax (in usd per share)	$ (1.43)	$ 0.57	$ 0.14	$ (0.13)	$ 0.36	$ 0.67	$ 0.11	$ (0.13)	$ (0.84)	$ 1.00	$ 0.79
Diluted, Net income (in usd per share)	$ (0.76)	$ 1.10	$ 0.76	$ 0.43	$ 0.73	$ 1.21	$ 0.68	$ 0.39	$ 1.53	$ 3.00	$ 2.65
Restricted Stock [Member]
Common Shares Outstanding (Textual) [Abstract]
Outstanding shares not included in the computation of diluted earnings per share for both restricted stock and stock options (in shares)									1.4	1.6	1.4
Stock Options [Member]
Common Shares Outstanding (Textual) [Abstract]
Outstanding shares not included in the computation of diluted earnings per share for both restricted stock and stock options (in shares)									3.4	10.1	23.2