Segment Reporting (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Revenue	$ 3,884.9	$ 3,805.3	$ 7,384.0	$ 7,274.5
Americas
Revenue	2,428.6	2,364.1	4,627.1	4,515.0
Long-lived assets and goodwill	6,574.0	6,135.5	6,574.0	6,135.5
UNITED STATES
Revenue	2,190.5	2,146.3	4,198.0	4,104.5
EMEA
Revenue	1,056.1	1,046.7	2,002.4	2,008.2
Long-lived assets and goodwill	2,644.9	2,790.0	2,644.9	2,790.0
Asia Pacific
Revenue	400.2	394.5	754.5	751.3
Long-lived assets and goodwill	$ 532.9	$ 547.1	$ 532.9	$ 547.1