Revenue Recognition (Schedule of Effects of Adjustments) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Prepaid expenses and other current assets	$ 109.0	$ 45.2
Other long-term assets	127.5	89.2	$ 111.2
Deferred income taxes	2.8	32.1
Accumulated deficit	$ (423.5)	$ (211.4)