Earnings Per Share

6 Months Ended

Jun. 30, 2017

Earnings Per Share [Abstract]

Earnings Per Share

5. 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,
	2017		2016		2017		2016
Number of common shares outstanding at end of period		439.7		441.7		439.7		441.7
Effect of using weighted average common shares outstanding		2.2		2.3		1.9		3.3
Weighted average basic common shares outstanding		441.9		444.0		441.6		445.0
Dilutive effect of equity-based compensation awards and other contingently issuable shares(a)		2.5		2.7		2.8		2.5
Weighted average diluted common shares outstanding		444.4		446.7		444.4		447.5
Potentially issuable shares		8.4		10.1		8.4		10.1
Number of anti-dilutive potentially issuable shares excluded from diluted common shares outstanding		2.3		0.5		2.3		0.8

(a) As of January 1, 2017, we adopted ASU 2016-09 prospectively and no longer include excess tax benefits as assumed proceeds. See Note 1 for further discussion.