Net Income per Share (Tables)

12 Months Ended

Dec. 31, 2017

Earnings Per Share [Abstract]

Schedule of Calculation of Basic and Diluted Net Income Per Share

The Company computed basic and diluted net income per share as follows (in millions, except per share amounts):

	Years Ended December 31,
	2017		2016		2015
Numerator:
Net income	$	306.2	$	592.7	$	633.7
Denominator:
Weighted-average shares used to compute basic net income per share	377.7		381.7		390.6
Dilutive effect of employee stock awards	6.5		6.1		8.8
Weighted-average shares used to compute diluted net income per share	384.2		387.8		399.4
Net income per share:
Basic	$	0.81	$	1.55	$	1.62
Diluted	$	0.80	$	1.53	$	1.59
Anti-dilutive shares	1.1		2.5		3.4