Shareholders' Equity - Data for stock options issued under the stock incentive plans (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding at January 1, 2018 | shares	3,467,340
Exercised | shares	(778,270)
Forfeited/Cancelled | shares	(21,628)
Outstanding at December 31, 2018 | shares	2,667,442
Options exercisable at December 31, 2018 | shares	2,253,003
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Average exercise price, Beginning balance | $ / shares	$ 45.80
Average exercise price, Exercised | $ / shares	37.66
Average exercise price, Forfeited/Cancelled | $ / shares	42.10
Average exercise price, Ending balance | $ / shares	48.20
Average exercise price, Options exercisable | $ / shares	$ 45.95
Average remaining contractual term, Options outstanding	4 years 2 months 12 days
Average remaining contractual term, Options exercisable	3 years 10 months 24 days
Aggregate intrinsic value, Options outstanding | $	$ 113
Aggregate intrinsic value, Options exercisable | $	$ 100