v3.20.4
Share-Based Payments (Summary of Stock Option Activity) (Details)
$ / shares in Units, shares in Millions, $ in Millions
12 Months Ended
Dec. 31, 2020
USD ($)
$ / shares
shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]  
Options outstanding at January 1, 2020 | shares 6.6
Options granted | shares 0.4
Options exercised | shares (1.3)
Options forfeited/expired | shares 0.0
Options outstanding at December 31, 2020 | shares 5.7
Options exercisable at December 31, 2020 | shares 3.8
Options vested and expected to vest at December 31, 2020 | shares 5.7
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]  
Weighted-average exercise price, options outstanding at January 1, 2020 | $ / shares $ 117
Weighted-average exercise price, options granted | $ / shares 263
Weighted-average exercise price, options exercised | $ / shares 75
Weighted-average exercise price, options forfeited/expired | $ / shares 229
Weighted-average exercise price, options outstanding at December 31, 2020 | $ / shares 137
Weighted-average exercise price, options exercisable at December 31, 2020 | $ / shares 106
Weighted-average exercise price, options vested and expected to vest at December 31, 2020 | $ / shares $ 137
Weighted-average remaining contractual term, options outstanding at December 31, 2020, in years 6 years
Weighted-average remaining contractual term, options exercisable at December 31, 2020, in years 5 years 1 month 6 days
Weighted-average remaining contractual term, options vested and expected to vest at December 31, 2020, in years 6 years
Aggregate intrinsic value, options outstanding at December 31, 2020 | $ $ 1,259
Aggregate intrinsic value, options exercisable at December 31, 2020 | $ 962
Aggregate intrinsic value, options vested and expected to vest at December 31, 2020 | $ 1,257
Stock Option  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount | $ $ 37
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period 10 years
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition 2 years 1 month 6 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]  
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period 4 years
Performance Shares  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]  
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period 3 years
Vesting period for retirement or disability | Stock Option  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]  
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period 7 months