EARNINGS PER SHARE

6 Months Ended

Jun. 30, 2017

A reconciliation of net income and shares used to calculate basic and diluted earnings per share is as follows (dollars in millions and shares in thousands):



	Three months ended				Six months ended
	June 30,				June 30,
	2017		2016		2017		2016
Net income for basic and diluted earnings per share	$	83.4	$	59.9	$	145.7	$	105.4
Shares:
Weighted average shares outstanding for basic earnings per share	170,556		178,323		171,994		179,337
Effect of dilutive securities on weighted average shares:
Stock options, restricted stock and performance units	1,796		1,944		1,714		1,861
Weighted average shares outstanding for diluted earnings per share	172,352		180,267		173,708		181,198

Basic earnings per common share is computed by dividing net income by the weighted average number of common shares outstanding for the period. Restricted shares (including our performance units) are not included in basic earnings per share until vested. Diluted earnings per share reflect the potential dilution that could occur if outstanding stock options were exercised and restricted stock was vested. The dilution from options and restricted shares is calculated using the treasury stock method. Under this method, we assume the proceeds from the exercise of the options (or the unrecognized compensation expense with respect to restricted stock and performance units) will be used to purchase shares of our common stock at the average market price during the period, reducing the dilutive effect of the exercise of the options (or the vesting of the restricted stock and performance units).