Earnings Per Share (Tables)

12 Months Ended

Dec. 31, 2017

Earnings Per Share [Abstract]

Schedule of Weighted Average Shares Outstanding Used to Compute Earnings Per Common Share

The weighted average number of shares outstanding used to compute earnings per common share were as follows (in millions):

	2017	2016	2015
Weighted average common shares outstanding for basic computations	287.8	299.3	310.3
Weighted average dilutive effect of equity awards	2.8	3.8	4.4
Weighted average common shares outstanding for diluted computations	290.6	303.1	314.7