Revenues, Unbilled Revenue and Deferred Revenue (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Contracts with Customers, Assets and Liabilities [Abstract]
Unbilled revenue	$ 223.8	$ 13.3
Deferred revenue	329.6	$ 291.2
Other Current Assets [Member]
Contracts with Customers, Assets and Liabilities [Abstract]
Unbilled revenue (current amount)	223.8
Other Current Liabilities [Member]
Contracts with Customers, Assets and Liabilities [Abstract]
Deferred revenue (current amount)	137.4
Other Liabilities [Member]
Contracts with Customers, Assets and Liabilities [Abstract]
Deferred revenue (noncurrent)	$ 192.2