Earnings Per Share

3 Months Ended

Jun. 30, 2012

Earnings Per Share [Abstract]

Earnings Per Share

6.    Earnings Per Share

Basic and diluted earnings per share were computed using the following common share data (shares in millions):

	Three Months Ended June 30,				Six Months Ended June 30,
	2012		2011		2012			2011
Number of common shares outstanding at end of period		463.0		472.3		463.0			472.3
Effect of using weighted average common shares outstanding		0.4		1.9		(0.1	)		2.6
Weighted average basic common shares outstanding		463.4		474.2		462.9			474.9
Dilutive effect of equity-based compensation awards and other contingently issuable shares		0.6		1.8		0.8			2.1
Weighted average diluted common shares outstanding		464.0		476.0		463.7			477.0
Potentially issuable shares		17.1		17.3		17.1			17.3
Number of anti-dilutive potentially issuable shares excluded from diluted common shares outstanding		8.3		6.1		8.2			6.1