Segment Information - Reconciliation of Revenue from Segments to Consolidated (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information [Line Items]
Revenues	$ 232.9	$ 459.9	$ 618.2	$ 831.6
Operating segments | U.S. Media
Segment Reporting Information [Line Items]
Revenues	213.5	419.6	568.2	758.0
Operating segments | Other
Segment Reporting Information [Line Items]
Revenues	$ 19.4	$ 40.3	$ 50.0	$ 73.6