Other Financial Information - Other Expense, Net (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other Financial Information [Abstract]
Interest income		$ 36.3	$ 79.1	$ 72.7
Interest expense		(77.0)	(88.7)	(103.2)
Gain (loss) on investments, net		13.3	(3.8)	(7.4)
Other		(5.5)	0.9	(1.6)
Other expense, net	[1]	$ (32.9)	$ (12.5)	$ (39.5)

[1] The amount for the year ended December 31, 2019 has been reclassified to conform to the current period presentation.