Shares Used In Computing Net Income Per Share (Details) In Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Shares Used In Computing Net Income Per Share [Abstract]
Weighted-average shares outstanding used for the calculation of net income per share-basic	141.1	149.7	143.2	151.2
Common stock equivalents	1.5	1.2	1.6	1.2
Total shares used for the calculation of net income per share-diluted	142.6	150.9	144.8	152.4
Stock options excluded from the calculation of diluted weighted-average outstanding shares because their impact was anti-dilutive	1.0	2.9	0.9	2.9