Earnings Per Share (Tables)

6 Months Ended

Jun. 30, 2012

Earnings Per Share [Abstract]

Average Common Shares Outstanding Basic and Diluted

	Three Months Ended June 30		Six Months Ended June 30
(Millions of shares)	2012	2011	2012	2011
Average shares outstanding	393.6	393.1	393.7	397.5
Participating securities	—	0.2	—	0.6
Basic	393.6	393.3	393.7	398.1
Dilutive effect of stock options	1.8	1.6	1.9	1.5
Dilutive effect of restricted share and restricted share unit awards	1.1	1.1	1.2	1.1
Diluted	396.5	396.0	396.8	400.7