Earnings Per Share

12 Months Ended

Dec. 31, 2011

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
	2011	2010	2009
	(Millions)
Average shares outstanding	395.4	411.3	414.6
Participating securities	0.3	1.1	1.5
Basic	395.7	412.4	416.1
Dilutive effect of stock options	1.6	1.1	0.4
Dilutive effect of restricted share and restricted share unit awards	1.3	0.9	0.3
Diluted	398.6	414.4	416.8

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:

	2011		2010		2009
Average number of share equivalents (millions)	3.6		13.9		21.8
Weighted-average exercise price	$	71.49	$	66.00	$	64.12
Expiration date of options	2011 to 2021		2010 to 2020		2009 to 2019
Options outstanding at year-end (millions)	3.0		14.7		20.3

The number of common shares outstanding as of December 31, 2011, 2010 and 2009 was 395.7 million, 406.9 million and 416.9 million, respectively.