Fair Value Of Assets And Liabilities - Reconciliation Of Balance, Fair Value Measurement, Level 3 (Details) - Contingent consideration liability - Significant Unobservable Inputs (Level 3) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance (Liability)	$ (33.6)	$ (38.4)	$ (60.2)	$ (40.9)
Revision to purchase price allocation	0.0		5.5
Purchases/acquisitions		(15.5)		(15.5)
Net unrealized gains and losses included in other gains and losses, net	3.2	0.5	11.4	(1.0)
Disposition/settlements	1.1	3.6	14.0	7.6
Ending balance (Liability)	$ (29.3)	$ (49.8)	$ (29.3)	$ (49.8)