Shares Used in Computing Net Income Per Share (Schedule of Weighted-Average Number of Shares) (Details) - shares shares in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Earnings Per Share [Abstract]
Weighted-average common shares outstanding used for the calculation of net income per share – basic (in shares)	222.0	236.5	222.8	237.6
Common stock equivalents (in shares)	3.6	3.9	3.7	4.1
Weighted-average common shares outstanding used for the calculation of net income per share – diluted (in shares)	225.6	240.4	226.5	241.7