Goodwill and Intangible Assets - Changes in Goodwill (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Changes in Goodwill:
Balance as of December 31, 2019	$ 7,631.4
Foreign currency translation	(69.6)
Balance as of June 30, 2020	7,561.8
Gross goodwill	8,200.0	$ 8,300.0
North America
Changes in Goodwill:
Balance as of December 31, 2019	6,146.6
Foreign currency translation	(9.4)
Balance as of June 30, 2020	6,137.2
Accumulated impairment losses	651.9	$ 681.3
Europe
Changes in Goodwill:
Balance as of December 31, 2019	1,484.8
Foreign currency translation	(60.2)
Balance as of June 30, 2020	$ 1,424.6