Pension And Other Benefit Plans - Components of Net Periodic Benefit Cost of Defined Benefit Pension Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ (10.3)	$ (9.1)	$ (10.0)
Net periodic pension cost	(11.2)	(7.6)	(7.3)
Defined benefit pension plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	(10.3)	(9.1)	(10.0)
Interest cost	(1.8)	(2.4)	(2.0)
Expected return on plan assets	3.8	3.2	3.8
Amortization of prior service credit and initial net obligation	0.2	(0.2)	(0.1)
Amortization of actuarial loss	(1.7)	(0.4)	(0.8)
Net settlement and curtailment (losses) gains	(1.4)	1.3	1.8
Net periodic pension cost	$ (11.2)	$ (7.6)	$ (7.3)