Segment Information Major Geographic Area (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues and Long-Lived Assets
Long-Lived Assets	$ 1,004.4				$ 906.8				$ 1,004.4	$ 906.8
Revenue	2,264.5	$ 1,922.2	$ 1,917.9	$ 1,742.0	2,196.2	$ 1,865.5	$ 1,876.1	$ 1,676.0	7,846.6	7,613.8	$ 7,537.1
Domestic
Revenues and Long-Lived Assets
Long-Lived Assets	684.8				600.1				684.8	600.1
Revenue									4,684.8	4,475.5	4,184.0
Total International
Revenues and Long-Lived Assets
Long-Lived Assets	319.6				306.7				319.6	306.7
Revenue									3,161.8	3,138.3	3,353.1
United Kingdom
Revenues and Long-Lived Assets
Long-Lived Assets	52.0				56.3				52.0	56.3
Revenue									695.7	687.7	688.3
Continental Europe
Revenues and Long-Lived Assets
Long-Lived Assets	57.0				58.6				57.0	58.6
Revenue									699.8	697.2	804.7
Asia Pacific
Revenues and Long-Lived Assets
Long-Lived Assets	118.3				114.9				118.3	114.9
Revenue									923.0	916.9	922.5
Latin America
Revenues and Long-Lived Assets
Long-Lived Assets	49.0				45.0				49.0	45.0
Revenue									372.7	383.5	470.4
Other
Revenues and Long-Lived Assets
Long-Lived Assets	$ 43.3				$ 31.9				43.3	31.9
Revenue									$ 470.6	$ 453.0	$ 467.2