Geographic Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information
Consolidated revenue	$ 2,412.4	$ 2,027.5	$ 2,239.6
Fixed assets (net)	73.9	79.6
United States
Segment Reporting Information
Consolidated revenue	1,838.7	1,524.0	1,642.2
Fixed assets (net)	58.7	64.2
United Kingdom
Segment Reporting Information
Consolidated revenue	528.6	462.3	515.2
Fixed assets (net)	14.6	14.6
Other
Segment Reporting Information
Consolidated revenue	45.1	41.2	$ 82.2
Fixed assets (net)	$ 0.6	$ 0.8