Supplemental Financial Statement Information - Severance and Employee Benefit Costs Rollforward (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Restructuring Reserve [Roll Forward]
Balance at December 31, 2020			$ 43.4
Payments			(12.4)
Balance at September 30, 2021	$ 21.8		21.8
Restructuring Cost and Reserve [Line Items]
Restructuring charges (credits)	$ (2.3)	$ 2.3	(8.5)	$ 27.0
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges (credits)			$ (9.2)