Pension and Other Postretirement Benefit Plans - Amounts Recognized in Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Pension | U.S.
Actuarial gains (losses) recognized:
Reclassification adjustments	$ 2.3	$ 1.8
Actuarial loss arising during the period	(46.1)	(21.7)
Effect of curtailment	0.0	0.0
Effect of settlements	0.3	0.1
Prior service credit recognized:
Reclassification adjustments	0.0	0.0
Prior service cost arising during the period	0.0	0.0
Translation adjustment	0.0	0.0
Pretax amounts recognized in other comprehensive (income) loss	(43.5)	(19.8)
Pension | Foreign
Actuarial gains (losses) recognized:
Reclassification adjustments	5.2	7.8
Actuarial loss arising during the period	(39.7)	(33.8)
Effect of curtailment	0.0	0.1
Effect of settlements	13.0	0.0
Prior service credit recognized:
Reclassification adjustments	0.0	0.0
Prior service cost arising during the period	0.0	0.0
Translation adjustment	(3.6)	(3.8)
Pretax amounts recognized in other comprehensive (income) loss	(25.1)	(29.7)
Other Postretirement | U.S.
Actuarial gains (losses) recognized:
Reclassification adjustments	(1.6)	(2.3)
Actuarial loss arising during the period	(6.9)	(4.5)
Effect of curtailment	0.0	0.0
Effect of settlements	0.0	0.0
Prior service credit recognized:
Reclassification adjustments	(0.2)	(0.2)
Prior service cost arising during the period	(0.4)	0.0
Translation adjustment	0.0	0.0
Pretax amounts recognized in other comprehensive (income) loss	(9.1)	(7.0)
Other Postretirement | Foreign
Actuarial gains (losses) recognized:
Reclassification adjustments	0.0	0.0
Actuarial loss arising during the period	(2.1)	0.0
Effect of curtailment	0.0	0.0
Effect of settlements	0.0	0.0
Prior service credit recognized:
Reclassification adjustments	0.0	(0.2)
Prior service cost arising during the period	0.0	0.0
Translation adjustment	0.0	0.0
Pretax amounts recognized in other comprehensive (income) loss	$ (2.1)	$ (0.2)