Reportable Business Segments and International Operations, Reconciliation of Segment Assets (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of segment assets to consolidated total assets
Segment assets excluding goodwill	$ 5,875.6	$ 5,886.7
Goodwill	4,867.1	4,103.2	$ 4,042.6
Other assets	72.8	55.0
Total assets	$ 10,815.5	$ 10,044.9