EARNINGS PER SHARE

Basic earnings per share is computed by dividing net income by the weighted-average common shares outstanding during a period. Diluted earnings per share is computed based on the weighted-average common shares outstanding plus the effect of dilutive potential common shares outstanding during the period calculated using the treasury stock method. Dilutive potential common shares include employee equity share options, nonvested shares, and similar equity instruments granted by the Company. Potential common share equivalents have been excluded where their inclusion would be anti-dilutive.

The table below presents the computation of basic and diluted earnings per share (in millions, except for per share information):



	Three Months Ended September 30,				Nine Months Ended September 30,
	2018		2017		2018		2017
Basic:
Net income	$	225.9	$	170.1	$	715.2	$	586.4
Weighted-average shares outstanding	209.0		211.3		209.5		211.0
Basic earnings per share	$	1.08	$	0.81	$	3.41	$	2.78
Diluted:
Net income	$	225.9	$	170.1	$	715.2	$	586.4
Weighted-average shares outstanding	209.0		211.3		209.5		211.0
Dilutive effect of stock plans	4.2		4.9		4.6		5.1
Dilutive weighted-average shares outstanding	213.2		216.2		214.1		216.1
Diluted earnings per share	$	1.06	$	0.79	$	3.34	$	2.71

Stock options, restricted stock units, and market-based restricted stock units to purchase 1.0 million and 2.1 million shares for the three months ended September 30, 2018 and 2017, respectively, and 1.1 million and 1.8 million shares for the nine months ended September 30, 2018 and 2017, respectively, were outstanding, but were not included in the computation of diluted earnings per share because the effect would have been anti-dilutive.