Annual report pursuant to Section 13 and 15(d)

Basis of Presentation - Computation of Basic and Diluted Earnings Per Share (Detail)

v3.8.0.1
Basis of Presentation - Computation of Basic and Diluted Earnings Per Share (Detail) - shares
shares in Millions
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Earnings Per Share [Abstract]      
Weighted average shares used in basic computations 79.2 83.0 82.6
Dilutive effect of exercise of equity grants outstanding 3.7 3.1 2.7
Weighted average shares used in diluted computations 82.9 86.1 85.3