Summary of Option Activity (Details) $ / shares in Units, shares in Millions, $ in Millions	9 Months Ended
	Sep. 30, 2019 USD ($) $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Beginning Balance, Options | shares	14.7
Granted, Options | shares	1.4
Exercised, Options | shares	(1.9)
Cancelled, Options | shares	(0.1)
Ending Balance, Options | shares	14.1
Exercisable at September 30, 2019, Options | shares	8.7
Beginning Balance, Weighted-Average Exercise Price | $ / shares	$ 37.63
Granted, Weighted-Average Exercise Price | $ / shares	77.30
Exercised, Weighted-Average Exercise Price | $ / shares	26.50
Cancelled, Weighted-Average Exercise Price | $ / shares	54.06
Ending Balance, Weighted-Average Exercise Price | $ / shares	43.02
Exercisable at September 30, 2019 Weighted-Average Exercise Price | $ / shares	$ 34.09
Outstanding at September 30, 2019, Weighted-Average Remaining Contractual Term, years	5 years 7 months 6 days
Exercisable at September 30, 2019, Weighted-Average Remaining Contractual Term, years	4 years
Outstanding at September 30, 2019, Aggregate Intrinsic Value | $	$ 456.7
Exercisable at September 30, 2019, Aggregate Intrinsic Value | $	$ 359.1