v3.7.0.1
Stock Plans (RSU Awards) (Details) - Restricted Stock Units (RSUs) [Member] - USD ($)
$ / shares in Units, $ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2017
Jun. 30, 2016
Jun. 30, 2017
Jun. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Number of Shares Granted (in shares)     1,202,970 1,212,050
Weighted-Average Grant Date Fair Value Per RSU Award Granted (in dollars per share)     $ 98.48 $ 89.02
Compensation expense for stock awards $ 25 $ 28 $ 60 $ 69