Other Financial Information - Other Expense, Net (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Other Financial Information [Abstract]
Interest income	$ 9.3	$ 19.8	$ 24.4	$ 43.3
Interest expense	(19.3)	(22.0)	(39.5)	(46.2)
Gain (loss) on investments, net	6.5	(2.8)	0.7	(1.2)
Other	(0.9)	0.4	(1.1)	1.3
Other (expense) income, net	$ (4.4)	$ (4.6)	$ (15.5)	$ (2.8)