Pension and Other Postretirement Benefit Plans - Components of Net Periodic Benefit Costs (Credit) (Details) - USD ($) $ in Millions	3 Months Ended			12 Months Ended
	Dec. 31, 2020	Oct. 03, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Settlement losses	$ 2.7	$ 10.2		$ 12.9
Foreign
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Curtailment (gain) loss			$ (12.9)
Pension | U.S.
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Service cost				0.1	$ 0.1	$ 0.1
Interest cost				16.4	18.6	19.8
Expected return on plan assets				(21.4)	(20.2)	(27.3)
Amortization of actuarial (gain) loss				2.3	1.8	2.0
Curtailment (gain) loss				0.0	0.0	0.0
Settlement losses				0.3	0.1	5.7
Net periodic benefit cost (credit)				(2.3)	0.4	0.3
Pension | Foreign
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Service cost				5.0	6.3	6.9
Interest cost				12.2	14.7	14.7
Expected return on plan assets				(19.6)	(20.9)	(23.0)
Amortization of actuarial (gain) loss				5.2	7.8	6.2
Curtailment (gain) loss				0.0	(2.3)	0.4
Settlement losses				13.0	0.0	0.0
Net periodic benefit cost (credit)				15.8	5.6	5.2
Other Postretirement | U.S.
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Service cost				0.0	0.0	0.0
Interest cost				1.7	2.1	1.9
Amortization of actuarial (gain) loss				(1.6)	(2.3)	(2.2)
Curtailment (gain) loss				0.0	0.0	0.0
Amortization of prior service credit				(0.2)	(0.2)	(0.2)
Net periodic benefit cost (credit)				(0.1)	(0.4)	(0.5)
Other Postretirement | Foreign
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Service cost				0.0	0.3	0.4
Interest cost				0.7	1.3	1.4
Amortization of actuarial (gain) loss				0.0	0.0	0.2
Curtailment (gain) loss				0.0	(10.6)	0.0
Amortization of prior service credit				0.0	(0.2)	(0.3)
Net periodic benefit cost (credit)				$ 0.7	$ (9.2)	$ 1.7