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, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance (Liability)	$ (4.4)	$ (33.6)	$ (18.6)	$ (60.2)
Purchases/acquisitions	(1.3)		(1.3)
Revision to purchase price allocation		0.0		(5.5)
Net unrealized gains and losses included in other gains and losses, net	(1.0)	3.2	4.7	11.4
Disposition/settlements	3.3	1.1	11.8	14.0
Ending balance (Liability)	$ (3.4)	$ (29.3)	$ (3.4)	$ (29.3)