Other Gains and Losses, Net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
OTHER GAINS AND LOSSES, NET
Gain on sale of investments	$ 0.0	$ 1.5	$ 6.9
Gain on equity investments and total return swap, net	41.7	82.5	0.0
Gain on contingent consideration liability	15.3	0.0	0.9
Net foreign exchange gains	0.1	0.0	0.0
Other realized gains	1.0	0.0	0.1
Non-service pensions gains	2.5	5.2	4.4
Total other gains	60.6	89.2	12.3
Other-than-temporary impairment of available-for-sale investments	(3.6)	(2.0)	(3.9)
Loss on equity investments and total return swap, net	0.0	0.0	(46.5)
Loss on contingent consideration liability	0.0	(7.8)	0.0
Net foreign exchange losses	(2.4)	(8.9)	(1.9)
Foreign exchange hedge loss	0.0	(4.8)	0.0
Non-service pension costs	(9.7)	0.0	0.0
Total other losses	(15.7)	(23.5)	(52.3)
Other gains and losses, net	$ 44.9	$ 65.7	$ (40.0)