Pension And Other Benefit Plans - Funded Status Of Pension Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Change in pension benefit obligation:
Service cost	$ (10.3)	$ (9.1)	$ (10.0)
Defined benefit pension plans
Change in pension benefit obligation:
Benefit obligation at beginning of year	(195.8)	(140.0)
Service cost	(10.3)	(9.1)	(10.0)
Interest cost	(1.8)	(2.4)	(2.0)
Employee contributions	(4.0)	(4.2)
Benefits and other expenses paid	5.1	6.2
Actuarial loss	(7.9)	(37.7)
Amendments, settlements and curtailments	28.5	(5.6)
Foreign exchange rate impact	(13.6)	(3.0)
Benefit obligation at end of year	(199.8)	(195.8)	(140.0)
Change in plan assets:
Fair value of plan assets at beginning of year	107.3	90.2
Actual return on plan assets	5.9	7.7
Employer contributions	8.3	8.2
Employee contributions	4.0	4.2
Amendments and settlements	(22.3)	0.8
Benefits and other expenses paid	(5.1)	(6.2)
Foreign exchange rate impact	7.6	2.4
Fair value of plan assets at end of year	105.7	107.3	$ 90.2
Funded status	$ (94.1)	$ (88.5)