Other Financial Information - Other Expense, Net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other Financial Information [Abstract]
Interest income	$ 79.1	$ 72.7	$ 53.0
Interest expense	(88.7)	(103.2)	(101.2)
Loss on extinguishment of debt	(15.3)	0.0	0.0
(Loss) gain on investments, net	(3.8)	(7.4)	14.6
Other	0.9	(1.6)	(2.7)
Other expense, net	$ (27.8)	$ (39.5)	$ (36.3)