Equity-Based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options outstanding, beginning (in shares)	3,781,051
Granted (in shares)	1,213,299
Forfeitures/Expired (in shares)	(59,834)
Exercised (in shares)	(476,520)
Options outstanding, ending (in shares)	4,457,996	3,781,051
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Options outstanding, beginning weighted-average exercise price (in dollars per share)	$ 29.36
Grants, weighted average exercise price (in dollars per share)	58.97
Forfeitures and Expirations, weighted average exercise price (in dollars per share)	45.76
Exercises, weighted average exercise price (in dollars per share)	27.37
Options outstanding, ending weighted-average exercise price (in dollars per share)	$ 37.41	$ 29.36
Options, outstanding, weighted average remaining contractual term	7 years 2 months 15 days
Options, outstanding intrinsic value	$ 143.0
Options, exercisable (in shares)	2,372,046
Options, exercisable, weighted average exercise price (in dollars per share)	$ 25.90
Options, exercisable, weighted average remaining contractual term (years)	5 years 11 months 19 days
Options, exercisable, Intrinsic Value	$ 103.4
Options, vested and expected to vest, Outstanding (in shares)	2,056,814
Options, vested and expected to vest, weighted average exercise price (in dollars per share)	$ 50.44
Options, vested and expected to vest, outstanding, weighted average remaining contractual term (in years)	8 years 7 months 9 days
Options, vested and expected to vest, aggregate intrinsic value	$ 39.2
Total intrinsic value of stock options exercised	$ 17.0	$ 7.0	$ 2.0