Pension and Other Post-Retirement Benefits - Pension Obligations, Plan Assets, and Other Post-retirement Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Change in Fair Value of Plan Assets
Plan assets at beginning of year	$ 432.7
Company contributions		$ 2.3	$ 2.3	$ 2.2
Plan assets at end of year	465.5	432.7
Amount Recognized
Other liabilities	(82.0)	(78.3)
Accumulative other comprehensive loss:
After-tax amount recognized in accumulated other comprehensive loss	79.2	85.4	92.6	$ 83.6
Defined Benefit Pension [Member]
Change in Benefit Obligation
Benefit obligation at beginning of year	475.4	413.7
Service cost	8.1	6.5	8.2
Interest cost	12.3	15.2	14.7
Actuarial loss	(45.2)	(63.7)
Benefits paid	33.4	24.9
Effect of foreign exchange rate changes	1.0	1.2
Benefit obligation at end of year	508.6	475.4	413.7
Change in Fair Value of Plan Assets
Plan assets at beginning of year	432.7	369.8
Actual return on plan assets	61.4	84.6
Effect of exchange rate changes	1.2	1.3
Company contributions	3.6	1.9
Benefits paid	(33.4)	(24.9)
Plan assets at end of year	465.5	432.7	369.8
Funded Status at end of year	(43.1)	(42.7)
Amount Recognized
Other liabilities	(43.1)	(42.7)
Accumulative other comprehensive loss:
Net actuarial loss	109.9	118.5
Prior service credit (cost)	0.0	0.0
Accumulated other comprehensive loss	109.9	118.5
Defined Benefit Plan, Amounts Recognized in Balance Sheet and Accumulated Other Comprehensive Income (Loss)	66.8	75.8
After-tax amount recognized in accumulated other comprehensive loss	82.2	88.6
Retiree Health and Life [Member]
Change in Benefit Obligation
Benefit obligation at beginning of year	24.6	27.5
Service cost	0.2	0.2	0.2
Interest cost	0.5	0.9	1.0
Actuarial loss	0.2	1.1
Benefits paid	2.2	2.9
Effect of foreign exchange rate changes	0.0	0.0
Benefit obligation at end of year	22.9	24.6	27.5
Change in Fair Value of Plan Assets
Plan assets at beginning of year	0.0	0.0
Actual return on plan assets	0.0	0.0
Effect of exchange rate changes	0.0	0.0
Company contributions	2.2	2.9
Benefits paid	(2.2)	(2.9)
Plan assets at end of year	0.0	0.0	$ 0.0
Funded Status at end of year	(22.9)	(24.6)
Amount Recognized
Other liabilities	(22.9)	(24.6)
Accumulative other comprehensive loss:
Net actuarial loss	(3.0)	(3.1)
Prior service credit (cost)	(1.0)	(1.2)
Accumulated other comprehensive loss	(4.0)	(4.3)
Defined Benefit Plan, Amounts Recognized in Balance Sheet and Accumulated Other Comprehensive Income (Loss)	(26.9)	(28.9)
After-tax amount recognized in accumulated other comprehensive loss	$ (3.0)	$ (3.2)