Earnings Per Share

12 Months Ended

Dec. 31, 2012

Earnings Per Share [Abstract]

Earnings Per Share

Earnings Per Share

A reconciliation of the average number of common shares outstanding used in the basic and diluted EPS computations follows:

	Average Common Shares Outstanding
	2012	2011	2010
	(Millions)
Average shares outstanding	393.0	395.4	411.3
Participating securities	—	0.3	1.1
Basic	393.0	395.7	412.4
Dilutive effect of stock options	1.8	1.6	1.1
Dilutive effect of restricted share unit awards	1.3	1.3	0.9
Diluted	396.1	398.6	414.4

Options outstanding that were not included in the computation of diluted EPS mainly because their exercise price was greater than the average market price of the common shares are summarized below:

	2012		2011		2010
Average number of share equivalents (millions)	1.1		3.6		13.9
Weighted-average exercise price	$	78.54	$	71.49	$	66.00
Options outstanding at year-end (millions)	1.7		3.0		14.7

The number of common shares outstanding as of December 31, 2012, 2011 and 2010 was 389.3 million, 395.7 million and 406.9 million, respectively.