Revenues, Unbilled Revenue and Deferred Revenue (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Contracts with Customers, Assets and Liabilities [Abstract]
Unbilled revenue	$ 66.5	$ 18.8
Deferred revenue	365.4	$ 343.5
Other Current Assets [Member]
Contracts with Customers, Assets and Liabilities [Abstract]
Unbilled revenue (current amount)	66.5
Other Current Liabilities [Member]
Contracts with Customers, Assets and Liabilities [Abstract]
Deferred revenue (current amount)	148.7
Other Liabilities [Member]
Contracts with Customers, Assets and Liabilities [Abstract]
Deferred revenue (noncurrent)	$ 216.7