Share-Based Compensation - Stock and Status (Details) - Stock options - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Options
Outstanding at beginning of the period (in shares)			8,088,680
Granted (in shares)			57,879
Exercised (in shares)	(333,049)	(25,000)	(346,549)	(191,508)
Forfeited/canceled (in shares)			(8,779)
Outstanding at the end of the period (in shares)	7,791,231		7,791,231
Exercisable at the end of the period (in shares)	4,974,974		4,974,974
Unvested at the end of the period (in shares)	2,816,257		2,816,257
Weighted Average Exercise Price
Outstanding at beginning of the period (in dollars per share)			$ 123.34
Granted (in dollars per share)			111.77
Exercised (in dollars per share)			64.54
Forfeited (in dollars per share)			135.48
Outstanding at the end of the period (in dollars per share)	$ 125.86		125.86
Exercisable at the end of the period (in dollars per share)	127.46		127.46
Unvested at the end of the period (in dollars per share)	$ 123.04		$ 123.04
Weighted Average Remaining Contractual Term (in Years)
Outstanding at the end of the period (in Years)			6 years
Exercisable at the end of the period (in Years)			5 years 6 months
Unvested at the end of the period (in Years)			7 years
Aggregate Intrinsic Value
Outstanding at the end of the period	$ 23.3		$ 23.3
Exercisable at the end of the period	33.8		33.8
Unvested at the end of the period	$ 10.5		$ 10.5
Weighted average grant date fair value of stock options (in dollars per share)			$ 35.53	$ 39.63
Aggregate grant date fair value			$ 2.1	$ 82.5
Total grant date fair value of employee stock options that vested			$ 72.7	$ 36.3