Net Income Per Share

The following table reconciles the shares used in the calculation of basic net income per share to those used for diluted net income per share:



	Three Months Ended September 30,				Nine Months Ended September 30,
(In millions)	2017		2016		2017		2016
Net income	$	51.0	$	37.6	$	150.7	$	104.5

Weighted average common shares outstanding	74.2		73.3		73.8		73.0
Dilutive effect of equity awards, based on the treasury stock method	1.7		1.7		2.0		1.7
Weighted average shares assuming dilution	75.9		75.0		75.8		74.7

During the three months ended September 30, 2017 and 2016, there were 0.5 million and 0.1 million shares, respectively, from stock-based compensation plans not included in the computation of diluted net income per share because their impact was antidilutive. There were 0.4 million and 0.1 million antidilutive shares outstanding during the nine months ended September 30, 2017 and 2016, respectively.

In December 2016, we announced a share repurchase program authorizing the repurchase of up to 800,000 shares of our common stock from time to time on the open market or in privately-negotiated transactions as permitted under the Securities Exchange Act of 1934 Rule 10b-18. The number of shares to be repurchased and the timing of such transactions will depend on a variety of factors, including market conditions. The program commenced on January 1, 2017 and is expected to be completed by December 31, 2017. There were no shares purchased during the three months ended September 30, 2017. During the nine months ended September 30, 2017, we purchased 325,000 shares of our common stock under the program at a cost of $26.9 million, or an average price of $82.84 per share.