Income per Share

3 Months Ended

Mar. 31, 2012

Income per Share [Abstract]

Income per Share

Note 7. Income per Share

Basic income per share is based on the weighted average number of common shares outstanding during the period. Diluted income per share includes additional common shares that would have been outstanding if potential common shares with a dilutive effect had been issued.

A reconciliation of the number of shares used for the basic and diluted income per share calculations is as follows:

	Three Months Ended March 31
Millions of shares	2012		2011
Basic weighted average common shares outstanding		923		914
Dilutive effect of employee stock plans		3		5
Diluted weighted average common shares outstanding		926		919

Excluded from the computation of diluted income per share are options to purchase five million shares of common stock that were outstanding during the three months ended March 31, 2012 and one million shares that were outstanding during the three months ended March 31, 2011. These options were outstanding during these periods but were excluded because they were antidilutive, as the option exercise price was greater than the average market price of the common shares.