Net Income Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Numerator:
Net income	$ 145.4	$ 99.3	$ 227.0	$ 176.6
Denominator:
Weighted-average shares used to compute basic net income per share (in shares)	330.9	342.2	330.9	345.5
Dilutive effect of employee stock awards (in shares)	3.6	3.3	4.3	4.6
Weighted-average shares used to compute diluted net income per share (in shares)	334.5	345.5	335.2	350.1
Net income per share
Basic (in dollars per share)	$ 0.44	$ 0.29	$ 0.69	$ 0.51
Diluted, (in dollars per share)	$ 0.43	$ 0.29	$ 0.68	$ 0.50
Anti-dilutive shares (in shares)	3.4	2.8	5.5	2.7