Segment Reporting (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Revenue	$ 3,805.3	$ 3,870.9	$ 7,274.5	$ 7,373.0
Americas
Revenue	2,364.1	2,295.2	4,515.0	4,376.3
Long-lived assets and goodwill	6,135.5	6,124.1	6,135.5	6,124.1
UNITED STATES
Revenue	2,146.3	2,061.3	4,104.5	3,933.1
EMEA
Revenue	1,046.7	1,173.9	2,008.2	2,235.6
Long-lived assets and goodwill	2,790.0	3,091.7	2,790.0	3,091.7
Asia Pacific
Revenue	394.5	401.8	751.3	761.1
Long-lived assets and goodwill	$ 547.1	$ 613.8	$ 547.1	$ 613.8