Segment Reporting (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue and Long-Lived Assets and Goodwill by Geographic Region
Revenue	$ 13,171.1	$ 14,953.7	$ 15,290.2
Americas
Revenue and Long-Lived Assets and Goodwill by Geographic Region
Revenue	7,852.5	8,882.2	8,900.0
Long-lived assets and goodwill	7,610.9	7,782.0	6,946.1
EMEA
Revenue and Long-Lived Assets and Goodwill by Geographic Region
Revenue	3,814.9	4,422.0	4,679.8
Long-lived assets and goodwill	3,142.3	3,061.3	2,578.9
Asia-Pacific
Revenue and Long-Lived Assets and Goodwill by Geographic Region
Revenue	1,503.7	1,649.5	1,710.4
Long-lived assets and goodwill	$ 665.1	$ 658.9	$ 553.7