Segment Information - Reconciliation of Assets from Segment to Consolidated (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Total assets	$ 5,887.1	$ 5,382.3
Operating segments | U.S. Media
Segment Reporting Information [Line Items]
Total assets	5,021.3	5,077.1
Operating segments | Other
Segment Reporting Information [Line Items]
Total assets	258.4	284.0
Corporate
Segment Reporting Information [Line Items]
Total assets	$ 607.4	$ 21.2