Stockholders' Equity (Details) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	3 Months Ended					1 Months Ended	3 Months Ended		1 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2012 Continuing operations	Mar. 31, 2011 Continuing operations	Mar. 31, 2011 Hewitt Associates, Inc (Hewitt)	Jan. 31, 2010 2010 - Share Repurchase Program	Mar. 31, 2012 2010 - Share Repurchase Program	Mar. 31, 2011 2010 - Share Repurchase Program	Apr. 30, 2012 2012 - Share Repurchase Program
Common Stock Programs
Share repurchase authorization limit						$ 2,000,000,000			$ 5,000,000,000
Number of shares repurchased							2.1	6.8
Average price per share of shares purchased under share repurchase program							$ 48.32	$ 51.29
Cost of shares repurchased	100,000,000						100,000,000	350,000,000
Cumulative number of shares purchased under share repurchase programs							18.2
Cumulative value of shares purchased under share repurchase programs							913,000,000
Number of shares issued for employee benefit plans					0.4
Number of treasury shares reissued for employee benefit plans	3.7	4.5
Number of treasury shares reissued for stock option exercises	1.0	2.0
Number of treasury shares reissued for employee stock purchase plans	0.3	0.1
Participating Securities
Income from continuing operations	$ 3,000,000	$ 4,000,000	$ 3,000,000	$ 4,000,000
Weighted average shares outstanding
Shares for basic earnings per share	332.4	339.4
Common stock equivalents (in shares)	4.2	6.0
Shares for diluted earnings per share	336.6	345.4
Number of participating securities (in shares)	4.9	5.7
Number of shares excluded from the calculation of diluted earnings per share	1	1