Contract Assets and Deferred Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Contract assets - current	$ 51.3		$ 51.3		$ 44.3
Contract assets - long-term	12.6		12.6		20.7
Deferred revenue - current	(224.2)		(224.2)		(257.1)
Deferred revenue - long-term	(153.0)		(153.0)		$ (137.9)
Revenue recognized that was included in deferred revenue at the beginning of the period	$ 47.5	$ 48.1	$ 210.4	$ 197.3