Segment Information - Geographic Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenues from external customers by geographic area
Total revenues	$ 401.5	$ 412.7	$ 1,137.7	$ 1,246.4
United States
Revenues from external customers by geographic area
Total revenues	359.4	389.0	1,028.4	1,177.1
Rest-of-World
Revenues from external customers by geographic area
Total revenues	$ 42.1	$ 23.7	$ 109.3	$ 69.3