Goodwill and Intangible Assets - Changes in Goodwill (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Changes in Goodwill:
Balance as of December 31, 2019	$ 7,631.4
Foreign currency translation	(7.3)
Balance as of September 30, 2020	7,624.1
Gross goodwill	8,300.0	$ 8,300.0
North America
Changes in Goodwill:
Balance as of December 31, 2019	6,146.6
Foreign currency translation	(5.4)
Balance as of September 30, 2020	6,141.2
Accumulated impairment losses	664.5	$ 681.3
Europe
Changes in Goodwill:
Balance as of December 31, 2019	1,484.8
Foreign currency translation	(1.9)
Balance as of September 30, 2020	$ 1,482.9