Share-Based Compensation - Stock Option Activity (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Balance at beginning of year (shares) | shares	3,683,786
Granted (shares) | shares	2,310,994
Exercised (shares) | shares	(569,146)
Canceled (shares) | shares	(137,657)
Balance at end of year (shares) | shares	5,287,977
Options exercisable at end of year (shares) | shares	2,339,904
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Balance at beginning of year (USD per share) | $ / shares	$ 19.59
Granted (USD per share) | $ / shares	76.22
Exercised (USD per share) | $ / shares	14.89
Canceled (USD per share) | $ / shares	48.31
Balance at end of year (USD per share) | $ / shares	44.10
Options exercisable at end of year (USD per share) | $ / shares	$ 21.11
Options outstanding, Weighted-Average Remaining Contractual Term (years)	7 years 8 months 12 days
Options exercisable, Weighted-Average Remaining Contractual Term (years)	6 years 1 month 6 days
Options outstanding, Aggregate Intrinsic Value | $	$ 448.2
Options exercisable, Aggregate Intrinsic Value | $	$ 252.1