Basic EPS is computed based upon the monthly weighted average number of common shares outstanding during each period. Diluted EPS is computed on the basis of the monthly weighted average number of common shares outstanding plus the potential dilutive effect if certain securities are converted into common shares. There were no antidilutive share awards outstanding for the three months ended March 31, 2012 and 2011.

		For the Three Months Ended March 31,
(Millions of Dollars, except share information)		2012		2011
Net Income Attributable to Controlling Interests		$	99.3	$	114.2

Weighted Average Common Shares Outstanding:
	Basic		178,055,716		177,188,207
	Dilutive Effect		381,737		292,789
	Diluted		178,437,453		177,480,996
Basic and Diluted EPS		$	0.56	$	0.64

RSUs and performance shares are included in basic weighted average common shares outstanding as of the date that all necessary vesting conditions have been satisfied. The dilutive effect of unvested RSUs and performance shares is calculated using the treasury stock method. Assumed proceeds of the units under the treasury stock method consist of the remaining compensation cost to be recognized and a theoretical tax benefit. The theoretical tax benefit is calculated as the tax impact of the intrinsic value of the units (the difference between the market value of the average units outstanding for the period, using the average market price during the period, and the grant date market value).

The dilutive effect of stock options to purchase common shares is also calculated using the treasury stock method. Assumed proceeds for stock options consist of remaining compensation cost to be recognized, cash proceeds that would be received upon exercise, and a theoretical tax benefit. The theoretical tax benefit is calculated as the tax impact of the intrinsic value of the stock options (the difference between the market value of the average stock options outstanding for the period, using the average market price during the period, and the exercise price).