Business Segments - Revenue and Long-Lived Assets by Geographic Segment (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
Geographic Segments
Total revenue	$ 752.2	$ 720.0	$ 729.2	$ 682.0	$ 737.0	$ 671.6	$ 691.5	$ 658.7	$ 2,883.4	$ 2,758.8	$ 1,786.4
Property and equipment, net	612.2				794.0				612.2	794.0
U.S.
Geographic Segments
Total revenue									1,959.0	2,144.0	1,070.1
Property and equipment, net	461.1				606.4				461.1	606.4
Other
Geographic Segments
Total revenue									924.4	614.8	$ 716.3
Property and equipment, net	$ 151.1				$ 187.6				$ 151.1	$ 187.6