v3.8.0.1
Share-Based Payments (Narrative) (Details) - USD ($)
$ / shares in Units, $ in Millions
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Tax benefit realized for exercises of stock options $ 39 $ 41 $ 20
Tax benefit realized upon vesting of restricted stock shares, restricted stock units, and performance shares 70 46 58
Cash used to settle performance units $ 27 $ 18 $ 21
Omnibus Incentive Plan      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Authorized shares remain available for grant including previously authorized but unissued shares under the Option Plan 23,092,637    
Employee stock options      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Maximum term of stock option granted (in years) 10 years    
Vesting period 3 years    
Weighed Average grant date fair value of stock options granted (in dollars per share) $ 27.91 $ 14.81 $ 18.45
The total intrinsic value of stock options exercised $ 109 $ 120 $ 49
Unrecognized Compensation Cost $ 3    
Weighted Average Recognition Period (in years) 1 year 7 months 20 days    
Employee Restricted Stock Restricted Units And Performance Shares      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
The fair market value of share awards released $ 196 $ 128 $ 162
Unrecognized Compensation Cost $ 152    
Weighted Average Recognition Period (in years) 1 year 8 months 16 days    
Employee restricted stock units      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Granted (in dollars per share) $ 110.39 $ 64.12 $ 78.4
Employee performance shares and performance units      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Granted (in dollars per share) $ 114.98 $ 104.06 $ 81.41