Retirement and Other Postretirement Benefit Plans - Schedule of Benefit Obligation, Fair Value of Plan Assets, Funded Status and Amounts Recognized in the Consolidated Financial Statements (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Change in plan assets:
Fair value of plan assets - beginning of year		$ 214.3
Fair value of plan assets - end of year		233.8	$ 214.3
Amounts recognized in Consolidated Balance Sheets:
Non-current liabilities		53.9	53.3
Postretirement Plans
Change in benefit obligation:
Benefit obligation - beginning of year		3.1	3.3
Interest cost		0.1	0.1	$ 0.1
Plan participants’ contributions			0.3
Actuarial loss (gain)		(0.5)	0.2
Benefits and expenses paid		(0.1)	(0.8)
Benefit obligation - end of year		2.6	3.1	3.3
Change in plan assets:
Employer contributions		0.1	0.5
Plan participants’ contributions			0.3
Benefits and expenses paid		(0.1)	(0.8)
Amounts recognized in Consolidated Balance Sheets:
Current liabilities		0.4	0.5
Non-current liabilities		2.2	2.6
Total liabilities	[1]	2.6	3.1
Amounts recognized in Accumulated Other Comprehensive Loss:
Actuarial net (loss) gain		1.6	1.8
Total amounts recognized in accumulated other comprehensive loss		1.6	1.8
U.S. Plans | Defined Benefit Retirement Plans
Change in benefit obligation:
Benefit obligation - beginning of year		20.3	18.2
Service cost		1.2	1.2	1.2
Interest cost		0.5	0.6	0.6
Actuarial loss (gain)		1.9	0.9
Benefits and expenses paid		(0.6)	(0.6)
Benefit obligation - end of year		23.3	20.3	18.2
Change in plan assets:
Employer contributions		0.6	0.6
Benefits and expenses paid		(0.6)	(0.6)
Amounts recognized in Consolidated Balance Sheets:
Current liabilities		3.8	1.4
Non-current liabilities		19.4	18.9
Total liabilities	[1]	23.2	20.3
Amounts recognized in Accumulated Other Comprehensive Loss:
Actuarial net (loss) gain		(4.5)	(3.0)
Total amounts recognized in accumulated other comprehensive loss		(4.5)	(3.0)
European Plans | Defined Benefit Retirement Plans
Change in benefit obligation:
Benefit obligation - beginning of year		188.6	160.9
Service cost		1.1	1.0	1.1
Interest cost		3.5	4.5	4.4
Actuarial loss (gain)		28.7	22.0
Curtailments and settlements		(3.2)	(0.4)
Benefits and expenses paid		(5.7)	(5.2)
Currency translation adjustments		7.9	5.8
Benefit obligation - end of year		220.9	188.6	160.9
Change in plan assets:
Fair value of plan assets - beginning of year		214.3	184.3
Actual return on plan assets		13.2	22.2
Employer contributions		5.7	5.2
Benefits and expenses paid		(5.8)	(5.2)
Curtailments and settlements		(0.9)	(0.2)
Currency translation adjustments		7.3	8.0
Fair value of plan assets - end of year		233.8	214.3	$ 184.3
Amounts recognized in Consolidated Balance Sheets:
Non-current assets		31.5	45.2
Current liabilities		0.9	0.6
Non-current liabilities		17.7	18.9
Total liabilities	[1]	18.6	19.5
Amounts recognized in Accumulated Other Comprehensive Loss:
Actuarial net (loss) gain		(50.1)	(28.8)
Prior service cost		(1.4)	(1.3)
Total amounts recognized in accumulated other comprehensive loss		$ (51.5)	$ (30.1)

[1] The current and non-current portions of the accrued benefit costs for the defined benefit retirement plans and postretirement benefit plans are included within “accrued compensation and benefits” and “retirement obligations”, respectively, in the accompanying consolidated balance sheets.