Segment Reporting (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenue and Long-Lived Assets and Goodwill by Geographic Region
Revenue	$ 3,719.8	$ 3,859.6	$ 7,188.7	$ 7,489.2
Americas
Revenue and Long-Lived Assets and Goodwill by Geographic Region
Revenue	2,215.3	2,212.5	4,293.4	4,306.6
Long-lived assets and goodwill	7,853.9	6,825.4	7,853.9	6,825.4
United States
Revenue and Long-Lived Assets and Goodwill by Geographic Region
Revenue	2,005.2	1,990.8	3,889.4	3,871.9
EMEA
Revenue and Long-Lived Assets and Goodwill by Geographic Region
Revenue	1,096.9	1,212.8	2,121.4	2,356.3
Long-lived assets and goodwill	2,985.0	2,757.9	2,985.0	2,757.9
Asia-Pacific
Revenue and Long-Lived Assets and Goodwill by Geographic Region
Revenue	407.6	434.3	773.9	826.3
Long-lived assets and goodwill	$ 640.9	$ 556.5	$ 640.9	$ 556.5