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 March 31,
(in millions)	2018		2017
Net income	$	43.6	$	60.9
Weighted average common shares outstanding	73.9		73.3
Dilutive effect of equity awards, based on the treasury stock method	1.6		1.6
Weighted average shares assuming dilution	75.5		74.9

During the three months ended March 31, 2018 and 2017, there were 0.7 million and 0.2 million shares, respectively, from stock-based compensation plans not included in the computation of diluted net income per share because their impact was antidilutive.

In February 2018, we announced a share repurchase program for calendar-year 2018 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 share repurchase program is expected to be completed by December 31, 2018. During the three months ended March 31, 2018, we purchased 540,000 shares of our common stock under the program at a cost of $47.9 million, or an average price of $88.74 per share.